->answer: Light is part of the electromagnetic spectrum, which ranges from radio waves to gamma rays. Like sound, light is a wave. . And light is a transverse wave (like a water wave). For its value, light is used mainly for industry and homes but, light still has deeper uses in our life. Sunlight on daytime is light, without it, how can we have energy to supply our needs? As we know that SUNLIGHT POWERS ALL LIFE ON earth. Light can also be created as an anti-HIV effect of hypericin as this article say; The requirement for light in the anti-HIV-1 activity of hypericin was investigated. The hypericin concentration-dependence and light dosage-dependence of the reaction were measured. Under conditions in which hypericin caused substantial inactivation of HIV-1, there was a strict requirement for visible light. Only when the concentration of hypericin approached the cytotoxic level was there an apparent light-independent antiviral effect. This strict light-requirement for the antiviral effect could explain some of the apparently discrepant results reported by other workers. Furthermore if hypericin is contemplated for use in humans, the importance of light must be considered. Light can also be used as a cure. Acne, wrinkles, viruses and more can be treated with light. Researchers are exploring everything from penetrating beams of light that seem to repair heart tissue after a heart attack to "light therapy" that appears to improve Alzheimer's patients' ability to sleep through the night. Doctors are remedying the side effects of cancer treatments, severe acne and other ailments just by shining high-intensity light in varying colors on the affected area. Exploring the whole value of light may keep you face a monitor for a whole day. That's all for the first assignment! Thank you! *end*
->answer: Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
For diurnal species (species that are active during the day), light is important for many reasons. Obviously, it is required for vision, and most birds have highly developed sight. For many species of animals, full-spectrum light is required for the conversion of cholesterol to vitamin D. Light and its changing cycles -- photoperiodicity is used by animals to synchronize their biological clocks. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals.
Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom. The extremely large eye leaves little room in the head for anything else. For example. an ostrich eye is 2 inches in diameter, an owl eye is one-third the entire head weight, and the buzzard eye has four times the visual acuity (sharpness) of a human eye.
Photoperiodicity has long been studied in birds as a means of inducing reproduction. Day length is detected by the pineal gland. The adrenal gland is located in the brain between the cerebella hemispheres and the cerebellum. It has numerous functions, one of which is photoreceptor and regulator of circadian rhythms. Some photoreceptors are located deep within the brain and are not dependent upon the eyes for photoreception. The hormones of the pineal gland (melatonin primarily) affect sleep, behavior and brain electrical activity. There is also evidence that melatonin influences reproductive hormonal cycles by affecting the pituitary gland. This has been very important in inducing poultry to lay eggs and to maximize egg production.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
Numerous breeders of exotic birds have used changing the day length in an attempt to manipulate breeding. however, few controlled studies have been conducted to assess its effects. Work at the department of avian sciences at the University of California at Davis and elsewhere demonstrated that long day lengths stimulate reproductive activity in cockatiels and blossom-headed parakeets. In general. birds must be exposed to short day lengths (10 hours of light, 14 hours of dark). before they can respond to long day lengths. The length of the photoperiod that may be stimulatory can only be determined experimentally for each species, but it may range from 13 to 17 hours. Ideally, it would increase gradually. Many birds will become unresponsive to this stimulus after prolonged! light stimulation. Work at UC Davis showed that cockatiels became resistant after two clutches. For pet birds, the sometimes prolonged or erratic photoperiods that they are exposed to in the home may affect them behaviorally. A bird exhibiting signs of sexual over stimulation or frustration (such as plucking) may respond to a shortened day length.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass.
->answer: There are many sources of light. The most common light sources are thermal: a body at a given temperature emits a characteristic spectrum of black-body radiation. Examples include sunlight (the radiation emitted by the chromosphere of the Sun at around 6,000 K peaks in the visible region of the electromagnetic spectrum), incandescent light bulbs (which emit only around 10% of their energy as visible light and the remainder as infrared), and glowing solid particles in flames. The peak of the blackbody spectrum is in the infrared for relatively cool objects like human beings. As the temperature increases, the peak shifts to shorter wavelengths, producing first a red glow, then a white one, and finally a blue color as the peak moves out of the visible part of the spectrum and into the ultraviolet. These colors can be seen when metal is heated to "red hot" or "white hot". The blue color is most commonly seen in a gas flame or a welder's torch.
Atoms emit and absorb light at characteristic energies. This produces "emission lines" in the spectrum of each atom. Emission can be spontaneous, as in light-emitting diodes, gas discharge lamps (such as neon lamps and neon signs, mercury-vapor lamps, etc.), and flames (light from the hot gas itself—so, for example, sodium in a gas flame emits characteristic yellow light). Emission can also be stimulated, as in a laser or a microwave maser.
Acceleration of a free charged particle, such as an electron, can produce visible radiation: cyclotron radiation, synchrotron radiation, and bremsstrahlung radiation are all examples of this. Particles moving through a medium faster than the speed of light in that medium can produce visible Cherenkov radiation.
Certain chemicals produce visible radiation by chemoluminescence. In living things, this process is called bioluminescence. For example, fireflies produce light by this means, and boats moving through water can disturb plankton which produce a glowing wake.
Certain substances produce light when they are illuminated by more energetic radiation, a process known as fluorescence. This is used in fluorescent lights. Some substances emit light slowly after excitation by more energetic radiation. This is known as phosphorescence.
Phosphorescent materials can also be excited by bombarding them with subatomic particles. Cathodoluminescence is one example of this. This mechanism is used in cathode ray tube televisions.
->answer: All animals are dependent on light to some extent, but birds are particularly sensitive to it. Birds deprived of sunlight may develop a variety of problems, including poor nutrient absorption, vitamin D deficiency, feather plucking, and disruption of mating and breeding patterns.
Many bird owners place their pet's cage near a window or other light source, but that may not be enough to cure the problem, since glass can act as a filter, reflecting instead of transmitting certain portions of the spectrum.
Dr. John Ott's research into the light needs of people, plants and animals led to the invention of full-spectrum lighting, a term coined by Ott. Full-spectrum lighting recreates the light-environment birds and others have in the wild. The poultry industry has already discovered that the benefits of providing full-spectrum lighting include increased egg production, larger eggs with stronger shells, and healthier birds.
What's the difference between a WIDE Spectrum and a FULL Spectrum light? It used to be that 'full spectrum' lighting meant lights which produced both ultraviolet B, ultraviolet A and the full visible spectrum as well infrared heat. Once incandescent manufacturers figured out that people were being told to look for 'full spectrum' lighting, they started to market their wide spectrum (producing some, but not all of the visible wavelengths and no ultraviolet wavelengths) lights with 'full spectrum' in the ads and on packaging. Thus people are buying Chromalux, NeoWhite and "Full Spectrum" incandescent lights thought, incorrectly, that they are providing UVB, UVA and full visible wavelengths to their birds. In fact, incandescents are just producing, if they are putting out bright white light, only the visible spectrum; some which produce colored light, are not necessarily even producing the full visible spectrum, being corrected to increase or reduce certain parts of that spectrum.
yOLight, form of energy visible to the human eye that is radiated by moving charged particles. Light from the Sun provides the energy needed for plant growth. Plants convert the energy in sunlight into storable chemical form through a process called photosynthesis. Petroleum, coal, and natural gas are the remains of plants that lived millions of years ago, and the energy these fuels release when they burn is the chemical energy converted from sunlight. When animals digest the plants and animals they eat, they also release energy stored by photosynthesis.
Light
Scientists have learned through experimentation that light behaves like a particle at times and like a wave at other times. The particle-like features are called photons. Photons are different from particles of matter in that they have no mass and always move at the constant speed of about 300,000 km/sec (186,000 mi/sec) when they are in a vacuum. When light diffracts, or bends slightly as it passes around a corner, it shows wavelike behavior. The waves associated with light are called electromagnetic waves because they consist of changing electric and magnetic fields.
II. THE NATURE OF LIGHT
Sidebars WORLD OF SCIENCE Scientists Create Matter Out of Light German-born American physicist Albert Einstein’s elegant equation E=mc2 predicted that energy could be converted to matter. Using a linear accelerator and high-energy laser light, physicists have done just that. This 1997 Encarta Yearbook article describes their success. open sidebar
To understand the nature of light and how it is normally created, it is necessary to study matter at its atomic level. Atoms are the building blocks of matter, and the motion of one of their constituents, the electron, leads to the emission of light in most sources.
Light can be emitted, or radiated, by electrons circling the nucleus of their atom. Electrons can circle atoms only in certain patterns called orbitals, and electrons have a specific amount of energy in each orbital. The amount of energy needed for each orbital is called an energy level of the atom. Electrons that circle close to the nucleus have less energy than electrons in orbitals farther from the nucleus. If the electron is in the lowest energy level, then no radiation occurs despite the motion of the electron. If an electron in a lower energy level gains some energy, it must jump to a higher level, and the atom is said to be excited. The motion of the excited electron causes it to lose energy, and it falls back to a lower level. The energy the electron releases is equal to the difference between the higher and lower energy levels. The electron may emit this quantum of energy in the form of a photon.
Each atom has a unique set of energy levels, and the energies of the corresponding photons it can emit make up what is called the atom’s spectrum. This spectrum is like a fingerprint by which the atom can be identified. The process of identifying a substance from its spectrum is called spectroscopy. The laws that describe the orbitals and energy levels of atoms are the laws of quantum theory. They were invented in the 1920s specifically to account for the radiation of light and the sizes of atoms.
B. Electromagnetic Waves
Electromagnetic Waves
The waves that accompany light are made up of oscillating, or vibrating, electric and magnetic fields, which are force fields that surround charged particles and influence other charged particles in their vicinity. These electric and magnetic fields change strength and direction at right angles, or perpendicularly, to each other in a plane (vertically and horizontally for instance). The electromagnetic wave formed by these fields travels in a direction perpendicular to the field’s strength (coming out of the plane). The relationship between the fields and the wave formed can be understood by imagining a wave in a taut rope. Grasping the rope and moving it up and down simulates the action of a moving charge upon the electric field. It creates a wave that travels along the rope in a direction that is perpendicular to the initial up and down movement.
Because electromagnetic waves are transverse—that is, the vibration that creates them is perpendicular to the direction in which they travel, they are similar to waves on a rope or waves traveling on the surface of water. Unlike these waves, however, which require a rope or water, light does not need a medium, or substance, through which to travel. Light from the Sun and distant stars reaches Earth by traveling through the vacuum of space.
The waves associated with natural sources of light are irregular, like the water waves in a busy harbor. Scientists think of such waves as being made up of many smooth waves, where the motion is regular and the wave stretches out indefinitely with regularly spaced peaks and valleys. Such regular waves are called monochromatic because they correspond to a single color of light.
1. Wavelength, Frequency, and Amplitude
The wavelength of a monochromatic wave is the distance between two consecutive wave peaks. Wavelengths of visible light can be measured in meters or in nanometers (nm), which are one-billionth of a meter (or about 0.4 ten-millionths of an inch). Frequency corresponds to the number of wavelengths that pass by a certain point in space in a given amount of time. This value is usually measured in cycles per second, or hertz (Hz). All electromagnetic waves travel at the same speed, so in one second, more short waves will pass by a point in space than will long waves. This means that shorter waves have a higher frequency than longer waves. The relationship between wavelength, speed, and frequency is expressed by the equation: wave speed equals wavelength times frequency, or
c = lf
Where c is the speed of a light wave in m/sec (3x108 m/sec in a vacuum), l is the wavelength in meters, and f is the wave’s frequency in Hz.
The amplitude of an electromagnetic wave is the height of the wave, measured from a point midway between a peak and a trough to the peak of the wave. This height corresponds to the maximum strength of the electric and magnetic fields and to the number of photons in the light.
The electromagnetic spectrum refers to the entire range of frequencies or wavelengths of electromagnetic waves (see Electromagnetic Radiation). Light traditionally refers to the range of frequencies that can be seen by humans. The frequencies of these waves are very high, about one-half to three-quarters of a million billion (5 x 1014 to 7.5 x 1014) Hz. Their wavelengths range from 400 to 700 nm. X rays have wavelengths ranging from several thousandths of a nanometer to several nanometers, and radio waves have wavelengths ranging from several meters to several thousand meters.
Waves with frequencies a little lower than the range of human vision (and with wavelengths correspondingly longer) are called infrared. Waves with frequencies a little higher and wavelengths shorter than human eyes can see are called ultraviolet. About half the energy of sunlight at Earth’s surface is visible electromagnetic waves, about 3 percent is ultraviolet, and the rest is infrared.
Each different frequency or wavelength of visible light causes our eye to see a slightly different color. The longest wavelength we can see is deep red at about 700 nm. The shortest wavelength humans can detect is deep blue or violet at about 400 nm. Most light sources do not radiate monochromatic light. What we call white light, such as light from the Sun, is a mixture of all the colors in the visible spectrum, with some represented more strongly than others. Human eyes respond best to green light at 550 nm, which is also approximately the brightest color in sunlight at Earth’s surface.
Polarization refers to the direction of the electric field in an electromagnetic wave. A wave whose electric field is oscillating in the vertical direction is said to be polarized in the vertical direction. The photons of such a wave would interact with matter differently than the photons of a wave polarized in the horizontal direction. The electric field in light waves from the Sun vibrates in all directions, so direct sunlight is called unpolarized. Sunlight reflected from a surface is partially polarized parallel to the surface. Polaroid sunglasses block light that is horizontally polarized and therefore reduce glare from sunlight reflecting off horizontal surfaces.
C. Photons
Photons may be described as packets of light energy, and scientists use this concept to refer to the particle-like aspect of light. Photons are unlike conventional particles, such as specks of dust or marbles, however, in that they are not limited to a specific volume in space or time. Photons are always associated with an electromagnetic wave of a definite frequency. In 1900 the German physicist Max Planck discovered that light energy is carried by photons. He found that the energy of a photon is equal to the frequency of its electromagnetic wave multiplied by a constant called h, or Planck's constant. This constant is very small because one photon carries little energy. Using the watt-second, or joule, as the unit of energy, Planck’s constant is 6.626 x 10-34 (a decimal point followed by 33 zeros and then the number 6626) joule-seconds in exponential notation. The energy consumed by a one-watt light bulb in one second, for example, is equivalent to two and a half million trillion photons of green light. Sunlight warms one square meter at the top of Earth’s atmosphere at noon at the equator with the equivalent of about 14 100-watt light bulbs. Light waves from the Sun, therefore, produce a very large number of photons.
Scientists have learned through experimentation that light behaves like a particle at times and like a wave at other times. The particle-like features are called photons. Photons are different from particles of matter in that they have no mass and always move at the constant speed of about 300,000 km/sec (186,000 mi/sec) when they are in a vacuum. When light diffracts, or bends slightly as it passes around a corner, it shows wavelike behavior. The waves associated with light are called electromagnetic waves because they consist of changing electric and magnetic fields.
II. THE NATURE OF LIGHT
Sidebars WORLD OF SCIENCE Scientists Create Matter Out of Light German-born American physicist Albert Einstein’s elegant equation E=mc2 predicted that energy could be converted to matter. Using a linear accelerator and high-energy laser light, physicists have done just that. This 1997 Encarta Yearbook article describes their success. open sidebar
To understand the nature of light and how it is normally created, it is necessary to study matter at its atomic level. Atoms are the building blocks of matter, and the motion of one of their constituents, the electron, leads to the emission of light in most sources.
Light can be emitted, or radiated, by electrons circling the nucleus of their atom. Electrons can circle atoms only in certain patterns called orbitals, and electrons have a specific amount of energy in each orbital. The amount of energy needed for each orbital is called an energy level of the atom. Electrons that circle close to the nucleus have less energy than electrons in orbitals farther from the nucleus. If the electron is in the lowest energy level, then no radiation occurs despite the motion of the electron. If an electron in a lower energy level gains some energy, it must jump to a higher level, and the atom is said to be excited. The motion of the excited electron causes it to lose energy, and it falls back to a lower level. The energy the electron releases is equal to the difference between the higher and lower energy levels. The electron may emit this quantum of energy in the form of a photon.
Each atom has a unique set of energy levels, and the energies of the corresponding photons it can emit make up what is called the atom’s spectrum. This spectrum is like a fingerprint by which the atom can be identified. The process of identifying a substance from its spectrum is called spectroscopy. The laws that describe the orbitals and energy levels of atoms are the laws of quantum theory. They were invented in the 1920s specifically to account for the radiation of light and the sizes of atoms.
B. Electromagnetic Waves
Electromagnetic Waves
The waves that accompany light are made up of oscillating, or vibrating, electric and magnetic fields, which are force fields that surround charged particles and influence other charged particles in their vicinity. These electric and magnetic fields change strength and direction at right angles, or perpendicularly, to each other in a plane (vertically and horizontally for instance). The electromagnetic wave formed by these fields travels in a direction perpendicular to the field’s strength (coming out of the plane). The relationship between the fields and the wave formed can be understood by imagining a wave in a taut rope. Grasping the rope and moving it up and down simulates the action of a moving charge upon the electric field. It creates a wave that travels along the rope in a direction that is perpendicular to the initial up and down movement.
Because electromagnetic waves are transverse—that is, the vibration that creates them is perpendicular to the direction in which they travel, they are similar to waves on a rope or waves traveling on the surface of water. Unlike these waves, however, which require a rope or water, light does not need a medium, or substance, through which to travel. Light from the Sun and distant stars reaches Earth by traveling through the vacuum of space.
The waves associated with natural sources of light are irregular, like the water waves in a busy harbor. Scientists think of such waves as being made up of many smooth waves, where the motion is regular and the wave stretches out indefinitely with regularly spaced peaks and valleys. Such regular waves are called monochromatic because they correspond to a single color of light.
1. Wavelength, Frequency, and Amplitude
The wavelength of a monochromatic wave is the distance between two consecutive wave peaks. Wavelengths of visible light can be measured in meters or in nanometers (nm), which are one-billionth of a meter (or about 0.4 ten-millionths of an inch). Frequency corresponds to the number of wavelengths that pass by a certain point in space in a given amount of time. This value is usually measured in cycles per second, or hertz (Hz). All electromagnetic waves travel at the same speed, so in one second, more short waves will pass by a point in space than will long waves. This means that shorter waves have a higher frequency than longer waves. The relationship between wavelength, speed, and frequency is expressed by the equation: wave speed equals wavelength times frequency, or
c = lf
Where c is the speed of a light wave in m/sec (3x108 m/sec in a vacuum), l is the wavelength in meters, and f is the wave’s frequency in Hz.
The amplitude of an electromagnetic wave is the height of the wave, measured from a point midway between a peak and a trough to the peak of the wave. This height corresponds to the maximum strength of the electric and magnetic fields and to the number of photons in the light.
The electromagnetic spectrum refers to the entire range of frequencies or wavelengths of electromagnetic waves (see Electromagnetic Radiation). Light traditionally refers to the range of frequencies that can be seen by humans. The frequencies of these waves are very high, about one-half to three-quarters of a million billion (5 x 1014 to 7.5 x 1014) Hz. Their wavelengths range from 400 to 700 nm. X rays have wavelengths ranging from several thousandths of a nanometer to several nanometers, and radio waves have wavelengths ranging from several meters to several thousand meters.
Waves with frequencies a little lower than the range of human vision (and with wavelengths correspondingly longer) are called infrared. Waves with frequencies a little higher and wavelengths shorter than human eyes can see are called ultraviolet. About half the energy of sunlight at Earth’s surface is visible electromagnetic waves, about 3 percent is ultraviolet, and the rest is infrared.
Each different frequency or wavelength of visible light causes our eye to see a slightly different color. The longest wavelength we can see is deep red at about 700 nm. The shortest wavelength humans can detect is deep blue or violet at about 400 nm. Most light sources do not radiate monochromatic light. What we call white light, such as light from the Sun, is a mixture of all the colors in the visible spectrum, with some represented more strongly than others. Human eyes respond best to green light at 550 nm, which is also approximately the brightest color in sunlight at Earth’s surface.
Polarization refers to the direction of the electric field in an electromagnetic wave. A wave whose electric field is oscillating in the vertical direction is said to be polarized in the vertical direction. The photons of such a wave would interact with matter differently than the photons of a wave polarized in the horizontal direction. The electric field in light waves from the Sun vibrates in all directions, so direct sunlight is called unpolarized. Sunlight reflected from a surface is partially polarized parallel to the surface. Polaroid sunglasses block light that is horizontally polarized and therefore reduce glare from sunlight reflecting off horizontal surfaces.
C. Photons
Photons may be described as packets of light energy, and scientists use this concept to refer to the particle-like aspect of light. Photons are unlike conventional particles, such as specks of dust or marbles, however, in that they are not limited to a specific volume in space or time. Photons are always associated with an electromagnetic wave of a definite frequency. In 1900 the German physicist Max Planck discovered that light energy is carried by photons. He found that the energy of a photon is equal to the frequency of its electromagnetic wave multiplied by a constant called h, or Planck's constant. This constant is very small because one photon carries little energy. Using the watt-second, or joule, as the unit of energy, Planck’s constant is 6.626 x 10-34 (a decimal point followed by 33 zeros and then the number 6626) joule-seconds in exponential notation. The energy consumed by a one-watt light bulb in one second, for example, is equivalent to two and a half million trillion photons of green light. Sunlight warms one square meter at the top of Earth’s atmosphere at noon at the equator with the equivalent of about 14 100-watt light bulbs. Light waves from the Sun, therefore, produce a very large number of photons.
The earliest speculations about light were hindered by the lack of knowledge about how the eye works. The Greek philosophers from as early as Pythagoras, who lived during the 5th century bc, believed light issued forth from visible things, but most also thought vision, as distinct from light, proceeded outward from the eye. Plato gave a version of this theory in his dialogue Timaeus, written in the 3rd century bc, which greatly influenced later thought.
Some early ideas of the Greeks, however, were correct. The philosopher and statesman Empedocles believed that light travels with finite speed, and the philosopher and scientist Aristotle accurately explained the rainbow as a kind of reflection from raindrops. The Greek mathematician Euclid understood the law of reflection and the properties of mirrors. Early thinkers also observed and recorded the phenomenon of refraction, but they did not know its mathematical law. The mathematician and astronomer Ptolemy was the first person on record to collect experimental data on optics, but he too believed vision issued from the eye. His work was further developed by Egyptian scientist Ibn al Haythen, who worked in Iraq and Egypt and was known to Europeans as Alhazen. Through logic and experimentation, Alhazen finally discounted Plato’s theory that vision issued forth from the eye. In Europe, Alhazen was the most well known among a group of Islamic scholars who preserved and built upon the classical Greek tradition. His work influenced all later investigations on light.
A. Early Scientific Theories
Sidebars WORLD OF SCIENCE A Dynamical Theory of the Electromagnetic Field British physicist James Clerk Maxwell, considered one of the 19th century’s most important scientists, was the first to demonstrate that light consists of electromagnetic waves. Building upon the ideas of British scientist Michael Faraday, Maxwell developed his electromagnetic theory of light. This and other works by Maxwell helped pave the way for some of the major advances in physics in the 20th century. The following is Maxwell’s treatise “A Dynamical Theory of the Electromagnetic Field” (1864), which contains the fundamental equations that describe the electromagnetic field. open sidebar
The early modern scientists Galileo, Johannes Kepler of Germany, and René Descartes of France all made contributions to the understanding of light. Descartes discussed optics and reported the law of refraction in his famous Discours de la méthode (Discourse on Method), published in 1637. The Dutch astronomer and mathematician Willebrord Snell independently discovered the law of refraction in 1620, and the law is now named after him.
During the late 1600s, an important question emerged: Is light a swarm of particles or is it a wave in some pervasive medium through which ordinary matter freely moves? English physicist Sir Isaac Newton was a proponent of the particle theory, and Huygens developed the wave theory at about the same time. At the time it seemed that wave theories could not explain optical polarization because waves that scientists were familiar with moved parallel, not perpendicular, to the direction of wave travel. On the other hand, Newton had difficulty explaining the phenomenon of interference of light. His explanation forced a wavelike property on a particle description. Newton’s great prestige coupled with the difficulty of explaining polarization caused the scientific community to favor the particle theory, even after English physicist Thomas Young analyzed a new class of interference phenomena using the wave theory in 1803.
Sidebars GREAT WORKS OF LITERATURE Newton on Light and Colors English physician, mathematician, and natural philosopher Sir Isaac Newton, one of the foremost figures in the history of Western science, produced insights into the natural world that were based on rigorously conducted experiments. Latin was the language of science at the time, but Newton also expressed himself in precise and direct English, as in this letter. Here, Newton reports on his experiments with prisms, which were begun in 1666 and led him to formulate a theory of the nature of light and color. open sidebar
The wave theory was finally accepted after French physicist Augustin Fresnel supported Young’s ideas with mathematical calculations in 1815 and predicted surprising new effects. Irish mathematician Sir William Hamilton clarified the relationship between wave and particle viewpoints by developing a theory that unified optics and mechanics. Hamilton’s theory was important in the later development of quantum mechanics.
Between the time of Newton and Fresnel, scientists developed mathematical techniques to describe wave phenomena in fluids and solids. Fresnel and his successors were able to use these advances to create a theory of transverse waves that would account for the phenomenon of optical polarization. As a result, an entire wave theory of light existed in mathematical form before British physicist James Clerk Maxwell began his work on electromagnetism. In his theory of electromagnetism, Maxwell showed that electric and magnetic fields affect each other in such a way as to permit waves to travel through space. The equations he derived to describe these electromagnetic waves matched the equations scientists already knew to describe light. Maxwell’s equations, however, were more general in that they described electromagnetic phenomena other than light and they predicted waves throughout the electromagnetic spectrum. In addition, his theory gave the correct speed of light in terms of the properties of electricity and magnetism. When German physicist Gustav Hertz later detected electromagnetic waves at lower frequencies, which the theory predicted, the basic correctness of Maxwell’s theory was confirmed.
Maxwell’s work left unsolved a problem common to all wave theories of light. A wave is a continuous phenomenon, which means that when it travels, its electromagnetic field must move at each of the infinite number of points in every small part of space. When we add heat to any system to raise its temperature, the energy is shared equally among all the parts of the system that can move. When this idea is applied to light, with an infinite number of moving parts, it appears to require an infinite amount of heat to give all the parts equal energy. But thermal radiation, the process in which heated objects emit electromagnetic waves, occurs in nature with a finite amount of heat. Something that could account for this process was missing from Maxwell’s theory. In 1900 Max Planck provided the missing concept. He proposed the existence of a light quantum, a finite packet of energy that became known as the photon.
B. Modern Theory
Planck’s theory remained mystifying until Einstein showed how it could be used to explain the photoelectric effect, in which the speed of ejected electrons was related not to the intensity of light but to its frequency. This relationship was consistent with Planck’s theory, which suggested that a photon’s energy was related to its frequency. During the next two decades scientists recast all of physics to be consistent with Planck’s theory. The result was a picture of the physical world that was different from anything ever before imagined. Its essential feature is that all matter appears in physical measurements to be made of quantum bits, which are something like particles. Unlike the particles of Newtonian physics, however, a quantum particle cannot be viewed as having a definite path of movement that can be predicted through laws of motion. Quantum physics only permits the prediction of the probability of where particles may be found. The probability is the squared amplitude of a wave field, sometimes called the wave function associated with the particle. For photons the underlying probability field is what we know as the electromagnetic field. The current world view that scientists use, called the Standard Model, divides particles into two categories: fermions (building blocks of atoms, such as electrons, protons, and neutrons), which cannot exist in the same place at the same time, and bosons, such as photons, which can (see Elementary Particles). Bosons are the quantum particles associated with the force fields that act on the fermions. Just as the electromagnetic field is a combination of electric and magnetic force fields, there is an even more general field called the electroweak field. This field combines electromagnetic forces and the weak nuclear force. The photon is one of four bosons associated with this field. The other three bosons have large masses and decay, or break apart, quickly to lighter components outside the nucleus of the atom.
Heheheh it's not easY to the Values of Light....For me light is valuable in all aspect in our life....sO thAt all foR the First onlin3 asSignment...!!!Thank you!!!
Light, form of energy visible to the human eye that is radiated by moving charged particles. Light from the Sun provides the energy needed for plant growth. Plants convert the energy in sunlight into storable chemical form through a process called photosynthesis. Petroleum, coal, and natural gas are the remains of plants that lived millions of years ago, and the energy these fuels release when they burn is the chemical energy converted from sunlight. When animals digest the plants and animals they eat, they also release energy stored by photosynthesis.
Light
Scientists have learned through experimentation that light behaves like a particle at times and like a wave at other times. The particle-like features are called photons. Photons are different from particles of matter in that they have no mass and always move at the constant speed of about 300,000 km/sec (186,000 mi/sec) when they are in a vacuum. When light diffracts, or bends slightly as it passes around a corner, it shows wavelike behavior. The waves associated with light are called electromagnetic waves because they consist of changing electric and magnetic fields.
II. THE NATURE OF LIGHT
Sidebars WORLD OF SCIENCE Scientists Create Matter Out of Light German-born American physicist Albert Einstein’s elegant equation E=mc2 predicted that energy could be converted to matter. Using a linear accelerator and high-energy laser light, physicists have done just that. This 1997 Encarta Yearbook article describes their success. open sidebar
To understand the nature of light and how it is normally created, it is necessary to study matter at its atomic level. Atoms are the building blocks of matter, and the motion of one of their constituents, the electron, leads to the emission of light in most sources.
Light can be emitted, or radiated, by electrons circling the nucleus of their atom. Electrons can circle atoms only in certain patterns called orbitals, and electrons have a specific amount of energy in each orbital. The amount of energy needed for each orbital is called an energy level of the atom. Electrons that circle close to the nucleus have less energy than electrons in orbitals farther from the nucleus. If the electron is in the lowest energy level, then no radiation occurs despite the motion of the electron. If an electron in a lower energy level gains some energy, it must jump to a higher level, and the atom is said to be excited. The motion of the excited electron causes it to lose energy, and it falls back to a lower level. The energy the electron releases is equal to the difference between the higher and lower energy levels. The electron may emit this quantum of energy in the form of a photon.
Each atom has a unique set of energy levels, and the energies of the corresponding photons it can emit make up what is called the atom’s spectrum. This spectrum is like a fingerprint by which the atom can be identified. The process of identifying a substance from its spectrum is called spectroscopy. The laws that describe the orbitals and energy levels of atoms are the laws of quantum theory. They were invented in the 1920s specifically to account for the radiation of light and the sizes of atoms.
B. Electromagnetic Waves
Electromagnetic Waves
The waves that accompany light are made up of oscillating, or vibrating, electric and magnetic fields, which are force fields that surround charged particles and influence other charged particles in their vicinity. These electric and magnetic fields change strength and direction at right angles, or perpendicularly, to each other in a plane (vertically and horizontally for instance). The electromagnetic wave formed by these fields travels in a direction perpendicular to the field’s strength (coming out of the plane). The relationship between the fields and the wave formed can be understood by imagining a wave in a taut rope. Grasping the rope and moving it up and down simulates the action of a moving charge upon the electric field. It creates a wave that travels along the rope in a direction that is perpendicular to the initial up and down movement.
Because electromagnetic waves are transverse—that is, the vibration that creates them is perpendicular to the direction in which they travel, they are similar to waves on a rope or waves traveling on the surface of water. Unlike these waves, however, which require a rope or water, light does not need a medium, or substance, through which to travel. Light from the Sun and distant stars reaches Earth by traveling through the vacuum of space.
The waves associated with natural sources of light are irregular, like the water waves in a busy harbor. Scientists think of such waves as being made up of many smooth waves, where the motion is regular and the wave stretches out indefinitely with regularly spaced peaks and valleys. Such regular waves are called monochromatic because they correspond to a single color of light.
1. Wavelength, Frequency, and Amplitude
The wavelength of a monochromatic wave is the distance between two consecutive wave peaks. Wavelengths of visible light can be measured in meters or in nanometers (nm), which are one-billionth of a meter (or about 0.4 ten-millionths of an inch). Frequency corresponds to the number of wavelengths that pass by a certain point in space in a given amount of time. This value is usually measured in cycles per second, or hertz (Hz). All electromagnetic waves travel at the same speed, so in one second, more short waves will pass by a point in space than will long waves. This means that shorter waves have a higher frequency than longer waves. The relationship between wavelength, speed, and frequency is expressed by the equation: wave speed equals wavelength times frequency, or
c = lf
Where c is the speed of a light wave in m/sec (3x108 m/sec in a vacuum), l is the wavelength in meters, and f is the wave’s frequency in Hz.
The amplitude of an electromagnetic wave is the height of the wave, measured from a point midway between a peak and a trough to the peak of the wave. This height corresponds to the maximum strength of the electric and magnetic fields and to the number of photons in the light.
The electromagnetic spectrum refers to the entire range of frequencies or wavelengths of electromagnetic waves (see Electromagnetic Radiation). Light traditionally refers to the range of frequencies that can be seen by humans. The frequencies of these waves are very high, about one-half to three-quarters of a million billion (5 x 1014 to 7.5 x 1014) Hz. Their wavelengths range from 400 to 700 nm. X rays have wavelengths ranging from several thousandths of a nanometer to several nanometers, and radio waves have wavelengths ranging from several meters to several thousand meters.
Waves with frequencies a little lower than the range of human vision (and with wavelengths correspondingly longer) are called infrared. Waves with frequencies a little higher and wavelengths shorter than human eyes can see are called ultraviolet. About half the energy of sunlight at Earth’s surface is visible electromagnetic waves, about 3 percent is ultraviolet, and the rest is infrared.
Each different frequency or wavelength of visible light causes our eye to see a slightly different color. The longest wavelength we can see is deep red at about 700 nm. The shortest wavelength humans can detect is deep blue or violet at about 400 nm. Most light sources do not radiate monochromatic light. What we call white light, such as light from the Sun, is a mixture of all the colors in the visible spectrum, with some represented more strongly than others. Human eyes respond best to green light at 550 nm, which is also approximately the brightest color in sunlight at Earth’s surface.
Polarization refers to the direction of the electric field in an electromagnetic wave. A wave whose electric field is oscillating in the vertical direction is said to be polarized in the vertical direction. The photons of such a wave would interact with matter differently than the photons of a wave polarized in the horizontal direction. The electric field in light waves from the Sun vibrates in all directions, so direct sunlight is called unpolarized. Sunlight reflected from a surface is partially polarized parallel to the surface. Polaroid sunglasses block light that is horizontally polarized and therefore reduce glare from sunlight reflecting off horizontal surfaces.
C. Photons
Photons may be described as packets of light energy, and scientists use this concept to refer to the particle-like aspect of light. Photons are unlike conventional particles, such as specks of dust or marbles, however, in that they are not limited to a specific volume in space or time. Photons are always associated with an electromagnetic wave of a definite frequency. In 1900 the German physicist Max Planck discovered that light energy is carried by photons. He found that the energy of a photon is equal to the frequency of its electromagnetic wave multiplied by a constant called h, or Planck's constant. This constant is very small because one photon carries little energy. Using the watt-second, or joule, as the unit of energy, Planck’s constant is 6.626 x 10-34 (a decimal point followed by 33 zeros and then the number 6626) joule-seconds in exponential notation. The energy consumed by a one-watt light bulb in one second, for example, is equivalent to two and a half million trillion photons of green light. Sunlight warms one square meter at the top of Earth’s atmosphere at noon at the equator with the equivalent of about 14 100-watt light bulbs. Light waves from the Sun, therefore, produce a very large number of photons.
Scientists have learned through experimentation that light behaves like a particle at times and like a wave at other times. The particle-like features are called photons. Photons are different from particles of matter in that they have no mass and always move at the constant speed of about 300,000 km/sec (186,000 mi/sec) when they are in a vacuum. When light diffracts, or bends slightly as it passes around a corner, it shows wavelike behavior. The waves associated with light are called electromagnetic waves because they consist of changing electric and magnetic fields.
II. THE NATURE OF LIGHT
Sidebars WORLD OF SCIENCE Scientists Create Matter Out of Light German-born American physicist Albert Einstein’s elegant equation E=mc2 predicted that energy could be converted to matter. Using a linear accelerator and high-energy laser light, physicists have done just that. This 1997 Encarta Yearbook article describes their success. open sidebar
To understand the nature of light and how it is normally created, it is necessary to study matter at its atomic level. Atoms are the building blocks of matter, and the motion of one of their constituents, the electron, leads to the emission of light in most sources.
Light can be emitted, or radiated, by electrons circling the nucleus of their atom. Electrons can circle atoms only in certain patterns called orbitals, and electrons have a specific amount of energy in each orbital. The amount of energy needed for each orbital is called an energy level of the atom. Electrons that circle close to the nucleus have less energy than electrons in orbitals farther from the nucleus. If the electron is in the lowest energy level, then no radiation occurs despite the motion of the electron. If an electron in a lower energy level gains some energy, it must jump to a higher level, and the atom is said to be excited. The motion of the excited electron causes it to lose energy, and it falls back to a lower level. The energy the electron releases is equal to the difference between the higher and lower energy levels. The electron may emit this quantum of energy in the form of a photon.
Each atom has a unique set of energy levels, and the energies of the corresponding photons it can emit make up what is called the atom’s spectrum. This spectrum is like a fingerprint by which the atom can be identified. The process of identifying a substance from its spectrum is called spectroscopy. The laws that describe the orbitals and energy levels of atoms are the laws of quantum theory. They were invented in the 1920s specifically to account for the radiation of light and the sizes of atoms.
B. Electromagnetic Waves
Electromagnetic Waves
The waves that accompany light are made up of oscillating, or vibrating, electric and magnetic fields, which are force fields that surround charged particles and influence other charged particles in their vicinity. These electric and magnetic fields change strength and direction at right angles, or perpendicularly, to each other in a plane (vertically and horizontally for instance). The electromagnetic wave formed by these fields travels in a direction perpendicular to the field’s strength (coming out of the plane). The relationship between the fields and the wave formed can be understood by imagining a wave in a taut rope. Grasping the rope and moving it up and down simulates the action of a moving charge upon the electric field. It creates a wave that travels along the rope in a direction that is perpendicular to the initial up and down movement.
Because electromagnetic waves are transverse—that is, the vibration that creates them is perpendicular to the direction in which they travel, they are similar to waves on a rope or waves traveling on the surface of water. Unlike these waves, however, which require a rope or water, light does not need a medium, or substance, through which to travel. Light from the Sun and distant stars reaches Earth by traveling through the vacuum of space.
The waves associated with natural sources of light are irregular, like the water waves in a busy harbor. Scientists think of such waves as being made up of many smooth waves, where the motion is regular and the wave stretches out indefinitely with regularly spaced peaks and valleys. Such regular waves are called monochromatic because they correspond to a single color of light.
1. Wavelength, Frequency, and Amplitude
The wavelength of a monochromatic wave is the distance between two consecutive wave peaks. Wavelengths of visible light can be measured in meters or in nanometers (nm), which are one-billionth of a meter (or about 0.4 ten-millionths of an inch). Frequency corresponds to the number of wavelengths that pass by a certain point in space in a given amount of time. This value is usually measured in cycles per second, or hertz (Hz). All electromagnetic waves travel at the same speed, so in one second, more short waves will pass by a point in space than will long waves. This means that shorter waves have a higher frequency than longer waves. The relationship between wavelength, speed, and frequency is expressed by the equation: wave speed equals wavelength times frequency, or
c = lf
Where c is the speed of a light wave in m/sec (3x108 m/sec in a vacuum), l is the wavelength in meters, and f is the wave’s frequency in Hz.
The amplitude of an electromagnetic wave is the height of the wave, measured from a point midway between a peak and a trough to the peak of the wave. This height corresponds to the maximum strength of the electric and magnetic fields and to the number of photons in the light.
The electromagnetic spectrum refers to the entire range of frequencies or wavelengths of electromagnetic waves (see Electromagnetic Radiation). Light traditionally refers to the range of frequencies that can be seen by humans. The frequencies of these waves are very high, about one-half to three-quarters of a million billion (5 x 1014 to 7.5 x 1014) Hz. Their wavelengths range from 400 to 700 nm. X rays have wavelengths ranging from several thousandths of a nanometer to several nanometers, and radio waves have wavelengths ranging from several meters to several thousand meters.
Waves with frequencies a little lower than the range of human vision (and with wavelengths correspondingly longer) are called infrared. Waves with frequencies a little higher and wavelengths shorter than human eyes can see are called ultraviolet. About half the energy of sunlight at Earth’s surface is visible electromagnetic waves, about 3 percent is ultraviolet, and the rest is infrared.
Each different frequency or wavelength of visible light causes our eye to see a slightly different color. The longest wavelength we can see is deep red at about 700 nm. The shortest wavelength humans can detect is deep blue or violet at about 400 nm. Most light sources do not radiate monochromatic light. What we call white light, such as light from the Sun, is a mixture of all the colors in the visible spectrum, with some represented more strongly than others. Human eyes respond best to green light at 550 nm, which is also approximately the brightest color in sunlight at Earth’s surface.
Polarization refers to the direction of the electric field in an electromagnetic wave. A wave whose electric field is oscillating in the vertical direction is said to be polarized in the vertical direction. The photons of such a wave would interact with matter differently than the photons of a wave polarized in the horizontal direction. The electric field in light waves from the Sun vibrates in all directions, so direct sunlight is called unpolarized. Sunlight reflected from a surface is partially polarized parallel to the surface. Polaroid sunglasses block light that is horizontally polarized and therefore reduce glare from sunlight reflecting off horizontal surfaces.
C. Photons
Photons may be described as packets of light energy, and scientists use this concept to refer to the particle-like aspect of light. Photons are unlike conventional particles, such as specks of dust or marbles, however, in that they are not limited to a specific volume in space or time. Photons are always associated with an electromagnetic wave of a definite frequency. In 1900 the German physicist Max Planck discovered that light energy is carried by photons. He found that the energy of a photon is equal to the frequency of its electromagnetic wave multiplied by a constant called h, or Planck's constant. This constant is very small because one photon carries little energy. Using the watt-second, or joule, as the unit of energy, Planck’s constant is 6.626 x 10-34 (a decimal point followed by 33 zeros and then the number 6626) joule-seconds in exponential notation. The energy consumed by a one-watt light bulb in one second, for example, is equivalent to two and a half million trillion photons of green light. Sunlight warms one square meter at the top of Earth’s atmosphere at noon at the equator with the equivalent of about 14 100-watt light bulbs. Light waves from the Sun, therefore, produce a very large number of photons.
The earliest speculations about light were hindered by the lack of knowledge about how the eye works. The Greek philosophers from as early as Pythagoras, who lived during the 5th century bc, believed light issued forth from visible things, but most also thought vision, as distinct from light, proceeded outward from the eye. Plato gave a version of this theory in his dialogue Timaeus, written in the 3rd century bc, which greatly influenced later thought.
Some early ideas of the Greeks, however, were correct. The philosopher and statesman Empedocles believed that light travels with finite speed, and the philosopher and scientist Aristotle accurately explained the rainbow as a kind of reflection from raindrops. The Greek mathematician Euclid understood the law of reflection and the properties of mirrors. Early thinkers also observed and recorded the phenomenon of refraction, but they did not know its mathematical law. The mathematician and astronomer Ptolemy was the first person on record to collect experimental data on optics, but he too believed vision issued from the eye. His work was further developed by Egyptian scientist Ibn al Haythen, who worked in Iraq and Egypt and was known to Europeans as Alhazen. Through logic and experimentation, Alhazen finally discounted Plato’s theory that vision issued forth from the eye. In Europe, Alhazen was the most well known among a group of Islamic scholars who preserved and built upon the classical Greek tradition. His work influenced all later investigations on light.
A. Early Scientific Theories
Sidebars WORLD OF SCIENCE A Dynamical Theory of the Electromagnetic Field British physicist James Clerk Maxwell, considered one of the 19th century’s most important scientists, was the first to demonstrate that light consists of electromagnetic waves. Building upon the ideas of British scientist Michael Faraday, Maxwell developed his electromagnetic theory of light. This and other works by Maxwell helped pave the way for some of the major advances in physics in the 20th century. The following is Maxwell’s treatise “A Dynamical Theory of the Electromagnetic Field” (1864), which contains the fundamental equations that describe the electromagnetic field. open sidebar
The early modern scientists Galileo, Johannes Kepler of Germany, and René Descartes of France all made contributions to the understanding of light. Descartes discussed optics and reported the law of refraction in his famous Discours de la méthode (Discourse on Method), published in 1637. The Dutch astronomer and mathematician Willebrord Snell independently discovered the law of refraction in 1620, and the law is now named after him.
During the late 1600s, an important question emerged: Is light a swarm of particles or is it a wave in some pervasive medium through which ordinary matter freely moves? English physicist Sir Isaac Newton was a proponent of the particle theory, and Huygens developed the wave theory at about the same time. At the time it seemed that wave theories could not explain optical polarization because waves that scientists were familiar with moved parallel, not perpendicular, to the direction of wave travel. On the other hand, Newton had difficulty explaining the phenomenon of interference of light. His explanation forced a wavelike property on a particle description. Newton’s great prestige coupled with the difficulty of explaining polarization caused the scientific community to favor the particle theory, even after English physicist Thomas Young analyzed a new class of interference phenomena using the wave theory in 1803.
Sidebars GREAT WORKS OF LITERATURE Newton on Light and Colors English physician, mathematician, and natural philosopher Sir Isaac Newton, one of the foremost figures in the history of Western science, produced insights into the natural world that were based on rigorously conducted experiments. Latin was the language of science at the time, but Newton also expressed himself in precise and direct English, as in this letter. Here, Newton reports on his experiments with prisms, which were begun in 1666 and led him to formulate a theory of the nature of light and color. open sidebar
The wave theory was finally accepted after French physicist Augustin Fresnel supported Young’s ideas with mathematical calculations in 1815 and predicted surprising new effects. Irish mathematician Sir William Hamilton clarified the relationship between wave and particle viewpoints by developing a theory that unified optics and mechanics. Hamilton’s theory was important in the later development of quantum mechanics.
Between the time of Newton and Fresnel, scientists developed mathematical techniques to describe wave phenomena in fluids and solids. Fresnel and his successors were able to use these advances to create a theory of transverse waves that would account for the phenomenon of optical polarization. As a result, an entire wave theory of light existed in mathematical form before British physicist James Clerk Maxwell began his work on electromagnetism. In his theory of electromagnetism, Maxwell showed that electric and magnetic fields affect each other in such a way as to permit waves to travel through space. The equations he derived to describe these electromagnetic waves matched the equations scientists already knew to describe light. Maxwell’s equations, however, were more general in that they described electromagnetic phenomena other than light and they predicted waves throughout the electromagnetic spectrum. In addition, his theory gave the correct speed of light in terms of the properties of electricity and magnetism. When German physicist Gustav Hertz later detected electromagnetic waves at lower frequencies, which the theory predicted, the basic correctness of Maxwell’s theory was confirmed.
Maxwell’s work left unsolved a problem common to all wave theories of light. A wave is a continuous phenomenon, which means that when it travels, its electromagnetic field must move at each of the infinite number of points in every small part of space. When we add heat to any system to raise its temperature, the energy is shared equally among all the parts of the system that can move. When this idea is applied to light, with an infinite number of moving parts, it appears to require an infinite amount of heat to give all the parts equal energy. But thermal radiation, the process in which heated objects emit electromagnetic waves, occurs in nature with a finite amount of heat. Something that could account for this process was missing from Maxwell’s theory. In 1900 Max Planck provided the missing concept. He proposed the existence of a light quantum, a finite packet of energy that became known as the photon.
B. Modern Theory
Planck’s theory remained mystifying until Einstein showed how it could be used to explain the photoelectric effect, in which the speed of ejected electrons was related not to the intensity of light but to its frequency. This relationship was consistent with Planck’s theory, which suggested that a photon’s energy was related to its frequency. During the next two decades scientists recast all of physics to be consistent with Planck’s theory. The result was a picture of the physical world that was different from anything ever before imagined. Its essential feature is that all matter appears in physical measurements to be made of quantum bits, which are something like particles. Unlike the particles of Newtonian physics, however, a quantum particle cannot be viewed as having a definite path of movement that can be predicted through laws of motion. Quantum physics only permits the prediction of the probability of where particles may be found. The probability is the squared amplitude of a wave field, sometimes called the wave function associated with the particle. For photons the underlying probability field is what we know as the electromagnetic field. The current world view that scientists use, called the Standard Model, divides particles into two categories: fermions (building blocks of atoms, such as electrons, protons, and neutrons), which cannot exist in the same place at the same time, and bosons, such as photons, which can (see Elementary Particles). Bosons are the quantum particles associated with the force fields that act on the fermions. Just as the electromagnetic field is a combination of electric and magnetic force fields, there is an even more general field called the electroweak field. This field combines electromagnetic forces and the weak nuclear force. The photon is one of four bosons associated with this field. The other three bosons have large masses and decay, or break apart, quickly to lighter components outside the nucleus of the atom.
Heheheh it's not easY to the Values of Light....For me light is valuable in all aspect in our life....sO thAt all foR the First onlin3 asSignment...!!!Thank you!!!
Light is everywhere in our world. We need it to see it carries information from the world to our eyes and brains. Seeing colors and shapes is second nature to us, yet light is a perplexing phenomenon when we study it more closely.
Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass
The correlation of light, melatonin regulation and its relevance to breast cancer has far-reaching implications for a 24-7 operation such as a hospital. Many theories have proposed that modern environmental causes such as electromagnetic fields or simple night-time light exposure increase the risk of breast cancer. This is true particularly if the night-time production of melatonin is interrupted, as melatonin has been shown to be part of the body’s natural defence against cancer. Taking such research into account, one can conclude that melatonin production will not be impaired when a room is in complete darkness or lit with the appropriate wavelength
->answer: Light is valuable. It is a form of energy. In fact, it can be converted into other forms. In plants, light is converted into chemical energy through the process of photosynthesis which occurs in leaves. Photographic film records images by converting light into chemical energy.
Other forms of energy can be converted into light. In most of our homes, electrical enerfy provides is with light. A candle flame produces light by converting chemical energy into light.
The Sun is the main source of energy on Earth. It supplies heat and light to warm the Earth and sustain life in it. Without light, there will be eternal darkness all over Earth.
Objects such as the Sun emit light. Others, such as an electric bulb, flashlight, burning candle and fire also emit light. These are called luminous bodies. Their light reaches our eyes and we see them.
Most objects around us are nonluminous. These do not emit light but illuminated by light from other sources. These interact with the light that hits them. Those which allow light to pass through are called transparent materials; while those which do not allow the passage of light are opaque. Light bounces off or reflects from opaque materials. All objects absorb energy from the light that hits them.
In terms of color, the energy of light that is absorbed is converted to heat, which warms the colored or black object. Objects such as flowers, leaves, paint, and dyes contain pigments that absorb certain colors and reflect others.
Light is simply a name for a range of electromagnetic radiation that can be detected by the human eye.
Electromagnetic radiation has a dual nature as both particles and waves. One way to look at it is as changing electric and magnetic fields which propagate through space, forming an electromagnetic wave. This wave has amplitude, which is the brightness of the light, wavelength, which is the color of the light, and an angle at which it is vibrating, called polarization.
Symbols exist in and throw persons. Symbols are the intermediary between the world internal and the world external, between inner and external reality of human being as a person. As Florensky wrote, symbols are the organs of our contact with reality. Symbols are openings that have pierced through in our subjectivity. Symbol is an integral and indivisible quality and the person can bear within him/herself this quality. The unique and unrepeatable person can contain within him/her the universal, as positive quality and attainment. According to Florensky, “Being has an inner aspect, which it turns towards itself, in its non-confusion with everything that is not itself; and an outer aspect, directed toward another being. There are the two aspects: they are not affixed to each other, but are in original unity. They are one and the same being, even if oriented in different directions. One aspect serves the self-affirmation of being; the other serves its revelation, its manifestation, its showing forth, or whatever name one might give to the life that connects one being with another. In the terminology of the ancients, these two aspects of being are called essence or substance, ousia, and activity or energy, energeia” (translated by Penny Burt). When the medieval thinkers say that every being has its energy, and that only non-being has none, this ontological axiom is fully approved by common sense. It means, after all, that everything that genuinely exists has life within itself and manifests that life, - testifies to its own existence - by a manifestation of its life, and in doing so, it testifies not to others only, but to itself as well. This manifestation of life is indeed the energy of being.
Symbol is a trace of sacred being in ordinary life. As Umberto Eco mentioned in “Symbol”, “Any symbol is an enigma”. Florensky defined symbol as “Being, when it’s more than itself, – this is the basic definition of a symbol. The symbol is something that reveals, through itself, that which is not itself, that which is more than itself, – and yet something that essentially announces itself through this symbol. Let’s unfold this formal definition: a symbol is that essence which fuses or mingles its energy with the energy of a more valuable essence. The symbol thereby carries within itself this more valuable essence” (translated by Penny Burt).
It is easily to say that “this more valuable essence” is God. But in our time, when struggle for freedom passed the boundary of Nietzsche’s "the God has died ", it resulted in the declaration that values of human life are not postulated on the basis of Absolute values any more. Disintegration of instances of the supreme values, ideas, and ideals entailed the mixture, flattening of noumenonality and phenomenonality. Even more, we can see through the majority of philosophical works that Society replaces God in contemporary understanding of world reality. The only one opportunity to reveal the sacred dimension of human being is to “return of the person”, as Paul Ricoeur suggested.
The person is ontological category. Person creates cosmos out of chaos. Person is possessed of cosmic beginning. According to Berdyaev, the affirmation of the supreme value of personality is not at all concern for personal salvation, but rather the expression of the person's supreme creative calling in the life of the world. It is possible because the “personality as an existential centre, presupposes capacity to feel suffering and joy. Nothing in the object world, nation or state or society, or social institution, or church, possesses this capacity” (Berdyaev). Person speaks not only as man belonging to the natural and social order, but also to a different dimension of being, to the spiritual world. Person is a form of being, higher than anything natural or social. Society is a small part of person, is merely its social condition, and the world is merely part of person. Person is the existential centre, not society and not nature. Person realizes itself in social and cosmic life, but it can do this only because that within it, it is independent from nature and from the principle of society. According to Berdyaev, the beginning of new epoch presupposes a change in human mentality, the liberation of man’s consciousness from the power of “objectness”.
Berdyaev vindicated the inequality, disparity of persons in the creativity. According to him, the temptation of an absolute equality leads to the extermination of all qualities and values, of all upsurges and ascents, in it -- is the spirit of non-being. Being was conceived in inequality, in a heightening of qualities, in individual distinctions. In it the star from star is distinguished in glory. The tendency in contemporary society to worship quantity over quality has subordinated human life to the caprice of the human passions, the interests and strivings for well-being and pleasure. Triumphant only are the utilitarian values. Everything is made subject to the good of individual people and to a mechanical quantity of people. The inward, the spiritual core of the human person is denied. Good and evil are acknowledged as relative and are evaluated as dependant upon societal usefulness. The consciousness of obligations was replaced by endless demands and pretensions. According to this world-view and world-sense, the person sets forth his demands and pretensions, independent of his qualities and services. Irresponsible pretentiousness paralyses the awareness of obligations. It is a moral ulcer, polluting our societal life. Berdyaev alerted that the "extinguishing of all qualitative distinctions" and of all the uplifting would be a return to the primordial non-being, wherewith is a complete equality, a total confusion. The uprising of the primordial chaotic non-being occurs periodically within history, whole societal movements can be reflective of its light.
The appeal to symbolic reality allows us to overcome personal boundaries. In Bakhtin’s words, person as “organic unity” is capable of “transcending itself that is, exceeding its own boundaries”. A “transcending of self” is the activity of “creation”. This personal activity translates belief into reality. And this closely resembles what we have called “the sacrifice of self”. To be open person needs to come into time. Time’s dimension from the beginning till end gives inner tension to human being between birth and death. This time’s perspective shapes possibility of identification with question “who is coming?’ Person tries to answer “It’s me”. Person exists as embodied person. It defines spatio-temporal life of person. This spatio-temporal dimension of person discovers his/her unique existence. This uniqueness shapes by fact of the death.
The unity of living person fixes by forthcoming death. Mikhail Bulgakov wrote in “The Master and Margarita”: “Yes, man is mortal, but that would be only half the trouble. The worst of it is that he's sometimes unexpectedly mortal - there’s the trick!” This unexpectedness allows person to feel vigilance. In this case person transcends spatio-temporal boundaries of “here and now” and uncovers activity itself. When the feeling of death becomes dull, the consciousness loses the alarm clock awaking to presence as to wakefulness. Then the soul alive has already finished his/her metamorphosis in “there-life”, and format Dasein is replaced by an empty shell. This felling of death pierces the personal existence and personality as an existential centre and presupposes capacity to feel suffering and joy. The sweetness of life arises from influence of the poison of death and the fact of desire occurs. Eternity calls never can permeate into motive of desire or even a simple inclination. Such motivation belongs only to mortal beings. The Beauty principally exists in the forms of deficit and scarcity because of complicacy to time unlike eternity. Socrates asserted that possibility to estimate a person life as happy or unfortunate arises only after death of the person. The life pierced by call of death discovers valuability.
The inequality of mortal persons is shown in all level of existence: in deep feelings of life and death, in intensity of life, in admissibility of present another, in symbolically equipped reality and especially in accesses to the centers of condensation of vitality itself. For the last one there is on the first place to be bodily demanded and beloved. Even further being in postmortality could develop differently for various persons. The degree of unpredictability here does not concede lifetime unpredictability. But anyway, it could open the new chance. For example, chance of ascension to true scales of the person which are not represented in given still-real body.
According to Florensky, a spatio-temporal actuality both is and is becoming, it is identical to itself both because it is a certain spatio-temporal actuality and because it is becoming a certain spatio-temporal actuality through its relatedness to other spatio-temporal actualities, and so the law of identity is always both grounded and violated. Thus, A is A and A is becoming A through not-A, i.e. through a denial of itself. He wrote, "each time it is necessary to become convinced not only of the truthfulness of the thesis p but also to clarify whether it is not half of some antinomy P" for the purpose of avoiding heresy ("hairesis [the Greek term] means choice, tendency, a disposition to something"), i.e. "a rational one-sidedness that claims to be everything".
It is necessary to clarify this understanding of spatio-temporal being by Florensky through his understanding of being itself. He explained the meaning of his “concrete metaphysics” in his work At the Watersheds of Thought (U vodorazdelov mysli) which is not translated in English yet. According to Florensky, we could say that being in full possession of itself is always present to itself. It means that being as essence discovers itself by surpassing. In existence being reveals itself as non-concealment. But in the act of revealing being keeps itself in this non-concealment and therefore being resides safety and is intact. In this case being is essence. This distinction in all-embracing unity of being is the difference between openness and safeness. This is tact or tune. Tact of “basing” and of “based” keeps this distinction in harmony. Essence and existence are intact. Here we can distinguish the inner Logos that is dividing the totality of existence from the revealed Logos. The Between which arises from this distinction highlights itself in the answering, as the one in the other. But it’s possible if being itself is all-embracing unity or being in superlative degree. From this it follows that the distinction by itself shows itself as being in its all-embracing unity and as being in a superlative degree.
Such understanding of being discovers two dimensions of personal being: 1) vertical dimension to all-embracing unity and to a superlative degree or perfectness; 2) horizontal dimension to just existence in ordinary life. Person's supreme creative calling in the life of the world presupposes holding of the exertion between these two dimensions of personal being. It’s better to understand the connection between these two dimensions of personal being through explanation of the connection between two beings by Florensky. He wrote: “the connection between beings – their mutual relation and revelation – is itself something real. Without breaking away from the centers that it connects, neither can it be reduced to them. This connection is synergy, the co-activity of beings. It necessarily reveals, through itself, both of the beings that it connects. It is not numerically identical to either being, since it is something new in relation to each one of them; but it is each one of them, since it is that which reveals the respective beings. After all, outside of and apart from its energy – and what’s more, an energy that has been assimilated – this being will remain not-discovered, not-revealed, not-known. And yet a certain energy of being can be assimilated only by the energy of the being that is doing the assimilating. If there is no medium for assimilating the stream of energy, i.e., if there is no stream of energy in response, then this means that the being on the receiving end has not shown itself as receiving, has not shown itself as actively receptive. Then, as far as the original stream of energy is concerned, this unresponsive being is – nothing: it might just as well not exist. Then the current of energy will go right through and pass this being by, without touching it, without noticing it, and without being perceived or noticed in return” (translated by Penny Burt).
Florensky tried to make it more clearly by the theory of resonance. There we cannot separate the oscillations of the resonance from the oscillations that give rise to the resonance. Florensky pointed that the resonance is no longer the activity of one circuit or the other, but the circuits’ co-activity. He elaborated the concept of synergy reasoning from it. What’s oscillating in the resonator is not only the resonator’s energy, nor the energy of the vibrator alone, but the synergy of both. And the presence of this synergy enables the two circuits, even if spatially separated, to become one. Florensky wrote: “Thus, resonance is synergy, the carrier of the beings that generate the resonance. It is more than itself: it is resonance and at the same time the cause of the resonance – that which causes the resonance to be. And, to that extent, it is the being that we regard as more valued and more important, inasmuch as it is more correct to give first place to the being that is revealed by its energy, and second place to the energy that does the revealing, but which derives its value and existence from the being which is its source. And so we’ve just hit upon the concept of a symbol” (translated by Penny Burt).
Each individual faces chaos in his own soul until he places himself in the context of his personal history. According to Florensky, “The life task of anyone is to perceive the structure and form of his family, its task, the law of its growth, its points of balance, the correlation of its different branches and their particular tasks, and, on the background of all this, to perceive one’s own place in one’s family and one’s own task, which is not one’s individual task, which one poses to oneself, but one’s task as the member of a family, as the organ of a greater whole.” Knowledge of one’s identity, as we would call it now, becomes possible only through diachronic self-analysis: “It is necessary to find one’s own place in history, to register oneself historically, to find one’s own coordinates in history, one’s genealogical latitude and longitude.” (Florensky)
Each embodied person has this genealogical latitude and longitude because of born from mother. This inheritance is mine, but not me. This is something which I have in deepness of myself, but it is still other than me. In 20th century this Otherness of me named unconsciousness. According to Freud, unconsciousness is a cauldron of seething desires, a bottomless pit of perverse and incestuous cravings. Unconsciousness’ demands push person to act in reality. The acting is blind without knowledge, but knowledge is lifeless without bottomless unconsciousness. Especially when we try to answer the question “Who I am?’ and look into deepness of our soul. As Carl Jung mentioned, if person would like to understand him/herself, it’s by “revivalist gatherings and ecstatic sects, through love and hate, through the experience of passion in every form in his own body, he would reap richer stores of knowledge than text-books a foot thick could give him”. According to Jung, unconsciousness influences all of our experiences and behaviors, most especially the emotional ones, but we only know about it indirectly, by looking at those influences. Jung suggested that we possess collective unconsciousness. It is the reservoir of our experiences as a species, a kind of knowledge we are all born with. The contents of the collective unconscious are called archetypes. Jung also called them dominants, imagos, mythological or primordial images, and a few other names, but archetypes seem to have won out over these. An archetype is an unlearned tendency to experience things in a certain way. It acts as an "organizing principle" on the things we see or do.
Umberto Eco describes Jung’s collective unconsciousness as symbolic reality. According to him, “The contents of the collective unconsciousness are the archetypes, archaic types, universal images, representations collectives: lunar, solar, vegetal, metereological representation, more comprehensible in myths, more evident in dreams and visions. Jung is explicit in saying that these symbols are neither mere signs (he uses the Greek technical word semeia) nor allegories. They are genuine symbols precisely because they are ambiguous, full of half-glimpsed meanings and in the last resorts inexhaustible. They are paradoxical because they are contradictory… If the archetypes are indescribable and infinitely interpretable, their experience cannot be but amorphous, undetermined, and unarticulated. Symbols are empty and full of meaning at the same time”.
Symbols hold two dimensions of human being: vertical and horizontal. By means of modern baggage of knowledge we could call symbols as archived files. But we should unarchive these files to identify ourselves. It could be done only by our own energy. According to Florensky, “I myself perceive this revelation to me and within me. As we’ve said, this revelation of essence is fused and mingled with the energy of my perception, laying the foundation for the entire further process of cognition. Hence, this further process of cognition in no way exceeds the original capacity of the fusion of energies, or synergy… The organ which establishes at will the connection between cognizer and cognized is the word, – and especially the name, or some equivalent that can be used as a name: the metonym” (translated by Penny Burt). Linguistics distinguishes between various forms of languages, but if the goal of all these activities is to express a meaning. Within the parameters of this single goal, activities which seem to differ quite radically are nonetheless united by a single common term: language. Florensky suggested that “The rational organism, as an integral whole, internally cohesive in many ways, responds to the energy of cognized reality with its whole being, not simply through some one of its functions…. there is really only one language – the language of the whole organism’s active self-manifestation; and only a single species of word – articulated by the whole body” (translated by Penny Burt). He mentioned that there may be some activity which turns out to be the shortest, and therefore the easiest, route to the discharge of inner energy, but the language of the articulate word is a universal instrument – the grand piano among the instruments of the spirit – the most many-sided and the most capable of serving the most various needs.
Words help us to unarchive archived files of symbols in our unconsciousness. This process preforms all the hues and directions of spiritual movements which might arise, so that each appearance of the spirit, the newest, most unexpected, the most uniquely-individual, all finds itself in such a word, finds itself a readied vessel, a ready home for its habitation. Florensky wrote: “it is the word alone, produced by the vocal organ, that makes the cognitive process possible, the word alone that makes objective what was still subjective and had not seemed even to ourselves to be the cognized truth before the word came along. On the other hand, the word pronounced sums up our inward longing for reality and places before us the cognitive urge (Sehnsucht) as a goal that has been achieved and a value that has been secured for consciousness” (translated by Penny Burt). To underline this point Florensky introduce the term isotrope from geometry. Geometry shows that however short (or long) the distance between two points in space may be, one can always construct a path along which this distance is equal to zero. The line of this path is the so-called isotrope. By establishing an isotropic connection between the points, we can make any two points directly contiguous to each other. Thus we can compare the word-utterance to this contact between cognizer and cognized along the isotrope: although remaining spatially separate, they prove to be mutually superimposed. The word is the ontological isotrope, according to Florensky. So the word is a bridge between the I and the non-I.
Words help us as certain operative system to unarchive files of collective memory. As Florensky wrote in The Pillar and Ground of the Truth: “The whole theory of knowledge is, in the final analysis, a theory of memory. Memory is the activity of assimilation in thought (i.e., creative reconstruction from representations) of that which is revealed by mystical experience in Eternity, or, in other words, the creation in Time of symbols of Eternity… One can touch once again the once-already-experienced time-transcending mystical reality that lay at the base of a single representation that has passed and that is to lie at the basis of another representation, which is coming and which is kindred to the first in the unity of mystical content.” Person uses old symbols, but fills them up with new senses. Florensky sees the process of cognition as creating on the lower planes models and schemes, and on the higher planes — symbols. According to Florensky, the symbol is the essence that carries the energy, grafted to its own, of another essence. And this other, second essence is revealed through the energy of the first – i.e., the symbol’s – essence.
But we should remember that symbolic reality holds vertical dimension of human life. This line has two orientations: to the up and to the down. Horizontal line of our ordinary life has direction from birth to death with machine coordinates. It specifies our life. Time is formed by concrete processes as a result of consecutive changes of its qualitatively new conditions. We can call this new concrete processes as detached processes, according to computer language. If there is no qualitative change, there is no time also. Time is always qualitative unity. Time opens the process of identification. The identification of qualitative unity in a time stream is possible in the presence of productive action. For this purpose, the person should understand aims of actions, means and tools for its achievement, and estimations of these actions depending both on the individual human factor, and on a cultural context as a whole.
To explain processes of “to be” and “to become” is better trough understanding of Time in Ancient Egyptian esoteric thought. There time itself was seen as having two distinct yet vital characteristics. These were expressed with two terms: neheh and djet. Instead of the three linear divisions of past, present and future, Egyptian language divided time into two ‘aspects’ which can best be understood by our concepts of ‘change’ and ‘completion’ or ‘perfection’. The concept of neheh is perhaps the closest to the modern perception of time. This is time an activity in progress or incomplete time. It is often said of neheh-time that it ‘comes’: it is time as an incessantly pulsating stream of days, months, seasons, and years. For the Egyptians ‘change’, as neheh-time, was seen as an ‘aspect’ or “representation”, as the ‘becoming one’. The conception of djet-time is considered an ‘aspect’ or ‘representation’. However, instead of the “becoming one” djet-time stresses the ‘completed one’ or “totality” in the sense of an ultimate and unalterable state of perfection. Djet-time is that which ‘remains,’ ‘lasts,’ and “endures” and this is the time in which we distinguish the completed. Djet-time belong to processes of the beyond world and to passive conditions, and neheh-time pertains to processes of real world and activity. To concern to this I would like to remain that in Russian language there is no future time and it sets a life “in the continued in infinity present”. Thus, the attempt to set action in the future or to set activity from the present into the future collides with unsolved problem at a level of grammar. There is no unequivocal form either for the first, or for the second in language itself. Russian language does not provide simpliciter for proper activity as a change of an external world or as a change of own attitude to the world.
Taking into account foresaid, we could say that symbols contain convoluted time of the concrete activity. The length of a time interval in a symbol is derivative from certain property and quality. By means of these the identification is attained, so as the self-sufficiency of the activity which necessary for the identification of the given detached process. Human activity is impossible without emotions and feelings. In accordance with this symbols fill with the potentiality of activity expressed in emotional, strong-willed concentration. They are able to reproduce plurality through singularity. From the one side, symbols create differentiation of the world of actions and forms cognitive space of the world. Cognitive space correlates with space of actions. There are the more differentiation, the more symbols and the richer cognitive space. Symbols are powerful because of potentiality of certain activity. And just of it they are fraught with danger. The same we can say about rituals as some sacred human activity. The goal of this expression is not the energies themselves – physical, occult, etc. – as registered from the outside, but rather the meaning which they introduce into the world. From the second side, we don’t know what we are doing by unarhiving of archived files. Opened activities could destroy not only somebody who discovered it, but whole system of the world. Plurality of symbols as a designation of the differentiated actions set richness and variety of processes and activities in the world and universe. Through the process of recombination the new symbol could be established. It is connected with previous symbols, but it possesses new unique inherent characteristics which distinguish it from previous qualitatively. It is possible to set some operations to join several symbols on the basis of plurality and diversity.
Symbolic reality contains chaos and cosmos as sacred by itself. The feeling of chaos creates three states which individuals find intolerable - analytic, emotional, and moral impotence. It gives rise to set religions. There are different etymological interpretations of this term: 1) as re-reading (from Latin re (again) + legio (read); 2) treating carefully (from Latin relegere); 3) re-connection (from Latin re (again) + ligare (to connect, as in English ligament). According to Geerts, religion is "...a system of symbols which acts to establish powerful, persuasive, and long-lasting moods and motivations in men [sic] by formulating conceptions of a general order of existence and clothing these conceptions with such an aura of factuality that the moods and motivations seem uniquely realistic". They are fused into what Geertz calls the "really real," which is created by "…the imbuing of a certain complex of symbols—of the metaphysics they formulate and the style of life which they recommend—with a persuasive authority which, from an analytic point of view is the essence of religious perspective". That is, these symbol systems make the ethos intellectually reasonable by being shown to represent a way of life adapted to the worldview, and to make the worldview emotionally convincing by being presented as an image well-suited to accommodate such a way of life.
Operation systems which unarchive symbols are languages. According to Umberto Eco we could call it semiotic drift, that is, the idea that by entering language we enter an unavoidable hermeneutic circle where nothing can limit the endless game of signification. But in the act of knowing we distinguish between the content of the act and its form – between what we know and how we know it. Florensky examined both orientations of thought which are already inherent in the spirit of the languages by analyzing the Aryan and Semitic language families. He wrote: “Through their etymology, the Semites have demonstrated that what they value in cognition is primarily reality, and in names – the objects, whereas the Aryans prize the rationality of the cognized, and in names – the concepts. On the one hand, nomen – omen, the name is a token; on the other, nomen – notio, the name is a concept. This is the antithesis between √shem and √gna, philosophically crowned by the names of Spinoza and Kant. If we delved into this antithesis, we would hit upon the theoretico-cognitive and then the ontological juxtaposition of the feminine receptive principle and the masculine normative one (Kabbalah)” (translated by Penny Burt).
According to Florensky, the cognized metaphysically enters into the cognizer, while the cognizer metaphysically comes out of himself, moves towards the cognized, vests it with himself. The first act is mystical perception, intrinsically mystical, whatever you may call it; while the second is the act of naming. By the first we embrace the cognized, and by the second we manifest ourselves in the world – in laboring towards the cognized. Word is orientated bilateral, first, from speaking - outside, as the activity interfering from speaking in external world, and secondly, from an external world to speaking, inside of it, as the perception received by speaking. In other words, the word will transform a life, and by a word a life is acquired to spirit. The word is magic and a word is mystical. To consider, why words are magical, it means to understand, how and why we can influence to the world by a word. Words are constructed by phonemes, morphemes and sememes. Especially the last one is created by participation of many generations of people. Sememe stays as if dead while the word is not used, but only it gets in a stream of alive speech sememe revives and still full of internal force and value. Word is the condenser of will, the condenser of attention, the condenser of all sincere life. Genes of whole person, genes of his/her personal genealogy to which he/she belongs emanate in speaking word.
Florensky wrote: “The purpose of the name was to pick out an object from the general chaos of impressions and to unite it with other objects, which had already been coordinated. The function of the name is to connect. The name de-solders the disorder of consciousness and solders together its order. It is both real and ideal. It is the beginning [arche] of articulation, the beginning of differentiation, the beginning of harmony and structure. In short, the name is not a sound, but a word, logos, i.e., the word as reason, sound as meaning, the one and the other merged together. And if this is so, then wasn’t Goethe right to translate the Word of the Gospel [John’s Logos] as Deed – Tat?. “In the beginning was the Deed [“Im Anfang war die Tat” – Faust One],” for only the word “name” can be a deed. In the word we partake of the Universal Word, Universal Reason, the Universal Deed, in which “we live, and move, and have our being [Acts 17:28]” (translated by Penny Burt).
We should remember that symbolic reality exists in and through person. The discovering of this reality is risky and danger for person. It opens vertical dimension of personal being with their up and down. Personal being as all-embracing unity including a superlative degree or perfectness presupposes the realization of either highermost and holy degree, or lowermost and sink degree. The lofty a person could rise, the below he/she could fall. In this sense, sincerely repented sinner is dear to the Lord than not sinned righteous person.
All of the following explain why is light valuable:
=>Light is produced by luminous objects, such as fires, electric lamps and stars like the Sun. The light that we can see is called visible light, but there is also light that we cannot see, including ultraviolet light and infrared light.
=>If you switch on an electric lamp, the light seems to come on instantly. However, the light doesn't really reach your eyes in no time at all. It just takes an extremely short time, because light travels extremely quickly. Light travels very much faster than sound, which is why you see lightning in a thunderstorm before you hear the thunder clap.
=>Light travels in straight lines. It cannot bend around corners, so we cannot see around a corner unless we use a mirror. We get shadows because light cannot bend round behind an object. When the Moon moves between the Sun and the Earth, it casts a shadow or "umbra" on the Earth. This blocks or partially blocks our view of the Sun, and it is called a solar eclipse.
=>Light cannot travel through opaque objects, such as brick walls. Opaque objects can cast dark shadows when light is shone on them. Light travels through transparent objects, such as glass windows. Paper and other translucent objects let some light through, but not all of it. This is why you can see the typing on the other side of a piece of printed paper if you hold it up to a light.
=>Light can travel through a vacuum such as space, but sound cannot. Science fiction films often show explosions in space with loud bangs. In real life, you would see the explosion but not hear it.
=>We see objects because light reflected from them enters our eyes. The light from luminous objects such as stars and lamps may enter our eyes directly. Non-luminous objects do not make their own light, but we can still see them if light from a luminous object reflects or scatters off them into our eyes.
=>The three primary colours of light are red, green and blue. If all three are mixed together, we get white light. If just two of them are mixed together, we get one of three secondary colours. The secondary colours are yellow, cyan and magenta. We can make any colour of light by mixing together a different amount of red, green or blue light.
=>Colour filters only let one colour of light through and stop the other colours. For example, a green filter stops all colours passing through except green. If a red or blue filter is then placed in front, no green light can pass through. If a colour is stopped by a filter we say that it is absorbed, and if a colour passes through a filter we say that it is transmitted.
=>Objects appear white if they can reflect all the colours of the spectrum. Objects appear black if they absorb all the colours of the spectrum.
=>Coloured objects reflect some colours and absorb others. For example, a green cloth reflects green light but absorbs the other colours of the spectrum.
=>Coloured objects have different colours in coloured light, because there are fewer colours for them to reflect. For example, in blue light:
=>a white cloth would appear blue, because there is only blue light for it to reflect; a black cloth would still appear black, because it absorbs all the light; a red cloth would appear black, because there is no red light for it to reflect.
=>Refraction happens as light enters and leaves a prism. Red light is refracted the least and violet light is refracted the most. This causes the different colours in the light to spread out to form a spectrum. Separating the colours like this is called dispersion. We say that the light has been dispersed.
=>The colours in the spectrum are red, orange, yellow, green, blue, indigo and violet. It may help to remember them using ROY G BIV or Richard Of York Gave Battle In Vain.
=>Water is denser than air, so light is refracted when it travels through the surface of the water. This is why sticks seem to be bent if they are partly underwater, and why swimming pools look shallower than they really are. Refraction lets you see objects that are normally hidden.
Light is essential to maintaining normal, healthy physiology. Exposure to sunrise is key to synchronizing our internal body cycles to the external world (so we sleep when it is dark and are alert during the day).
Modern industrial society began to tamper with this system, though. The loss of natural light - in dark apartments, in the workplace, on shift work, etc. - creates a state of light deprivation, making us vulnerable to depressed mood, sleep problems, fatigue, ability to concentrate, and more. Nature, too, posed a new problem when humans began to migrate north, where winter nights are long and dark.
Light levels as measured in lux vary greatly between indoor and outdoor lighting. You can see from the chart below how easy it is to become light deprived in our modern, indoor society.
im uber and out! thats all 4 today.......... see yah......... end
SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light. Earth would not have any life on it without the Sun’s energy, which reaches Earth in the form of heat and light. This energy warms our days and illuminates our world. Green plants absorb sunlight and convert it to food, which these plants then use to live and grow. In this process, the plants give off the oxygen that animals breathe. Animals eat these plants for nourishment. All plant and animal life relies on the Sun’s presence. Light is also essential for the survival of most animal species. The Sun also provides—directly or indirectly—much of the energy on Earth that people use for fuel ( Solar Energy) Devices called solar cells turn sunlight into electricity. Sunlight can heat a gas or liquid, which can then be circulated through a building to heat the building. The energy stored in fossil fuels originally came from the Sun. Ancient plants used sunlight as fuel to grow. Animals consumed these plants. The plants and animals stored the energy of sunlight in the organic material that composed them. When the ancient plants and animals died and decayed, this organic material was buried and gradually turned into the petroleum, coal, and natural gas people use today. The Sun’s energy produces the winds and the movements of water that people harness to produce electricity (see Wind Energy; Water Power). The Sun heats Earth’s oceans and land, which in turn heat the air and make it circulate in the atmosphere as wind. The Sun fuels Earth’s water cycle, evaporating water from the oceans, seas, and lakes. This water returns to the ground in the form of precipitation, flowing back to the oceans through the ground and in rivers. The energy of water’s motion in rivers can be harnessed with dams..... LIGHT as medicine.,., Niels Ryberg Finsen (1860-1904), Danish physician and Nobel Prize winner who made important discoveries regarding the use of light waves in the treatment of disease. Finsen was born in Tórshavn, the capital of the Faeroe Islands, a part of Denmark located north of the British Isles. After completing his early schooling in Denmark and in Reykjavík, Iceland, Finsen attended the University of Copenhagen in Denmark, receiving his medical degree in 1891. He then taught anatomy in the university's Department of Surgery, leaving in 1893 to devote himself full-time to studying “phototherapy,” or the therapeutic effects of light. In 1896 he established the Light Institute in Copenhagen. For his groundbreaking contributions to the new field of phototherapy, Niels Finsen received the 1903 Nobel Prize in physiology or medicine. Even as a child, Finsen had been fascinated by the effects of sunlight on living things. His research as an undergraduate included experiments in which he observed how sunlight affected the tissue of insects, tadpoles, and other animals. Later Finsen decided to turn his efforts toward the treatment of human diseases. In 1893 he began to study the use of filtered sunlight in the treatment of skin lesions caused by smallpox, a viral disease. Red light—that is, light from the red end of the spectrum—with its harmful heat rays filtered out, proved successful in promoting the healing of smallpox lesions. After publishing key papers on phototherapy in 1893 and 1894, Finsen began research into the treatment of lupus vulgaris, a disfiguring skin disease caused by bacteria. Finsen had noted the findings of previous researchers, who discovered that light could kill bacteria. Focusing an artificial light through a prism, Finsen exposed diseased tissue to high concentrations of ultraviolet light. The method proved highly effective in treating lupus vulgaris. Finsen established his Light Institute in Copenhagen, where hundreds of lupus vulgaris patients were successfully treated over the next few years. The use of ultraviolet light remained the central treatment for lupus vulgaris for decades.
Of course,light is very valuable specially to human,plants and animals.The sun is the ultimate source of energy.The sun our nearest star,is our main source of light.Although it is nearly 150 million kilometres away ,the light it makes reaches the Earth in only eight minutesand is so strong that it damages our eyes if we look straight at it At night we only use light bulbs or candles for light.Compared to the sun,the light energy made by these is tiny.they can only light up objects a few metres away.Nearly all of the light and energy reaching the Earth comes from the sun which is powered by continous thermonuclear reaction,like agigantic hydrogen bomb.The moon has no light of it's own-it shines only because it reflects the Sun's light stars,however are luminous because they produce their own light. Green plants and other producers transform light energy into chemical energy through the process called photosynthesis.Light is also an important factor in photosynthesis because it provides energy. When much light energy is absorbed,more chlorophyll molecules are energized,causing them to capture more energy that can be used in the chemical reaction producing glucose and starch. In our mirrors,Mirrors are coated with a reflective material, so when a beam of light strikes the surface none of it is absorbed.The beam of light is reflected away again.The light is reflected at exactly the same angleas it struck the mirror, but in the opposite direction this can be visualized as being similar to a snooker ball striking the cushion of the table and bouncing at an angle
->answer: Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
->answer: Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
For diurnal species (species that are active during the day), light is important for many reasons. Obviously, it is required for vision, and most birds have highly developed sight. For many species of animals, full-spectrum light is required for the conversion of cholesterol to vitamin D. Light and its changing cycles -- photoperiodicity is used by animals to synchronize their biological clocks. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals.
Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom. The extremely large eye leaves little room in the head for anything else. For example. an ostrich eye is 2 inches in diameter, an owl eye is one-third the entire head weight, and the buzzard eye has four times the visual acuity (sharpness) of a human eye.
Photoperiodicity has long been studied in birds as a means of inducing reproduction. Day length is detected by the pineal gland. The adrenal gland is located in the brain between the cerebella hemispheres and the cerebellum. It has numerous functions, one of which is photoreceptor and regulator of circadian rhythms. Some photoreceptors are located deep within the brain and are not dependent upon the eyes for photoreception. The hormones of the pineal gland (melatonin primarily) affect sleep, behavior and brain electrical activity. There is also evidence that melatonin influences reproductive hormonal cycles by affecting the pituitary gland. This has been very important in inducing poultry to lay eggs and to maximize egg production.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
Numerous breeders of exotic birds have used changing the day length in an attempt to manipulate breeding. however, few controlled studies have been conducted to assess its effects. Work at the department of avian sciences at the University of California at Davis and elsewhere demonstrated that long day lengths stimulate reproductive activity in cockatiels and blossom-headed parakeets. In general. birds must be exposed to short day lengths (10 hours of light, 14 hours of dark). before they can respond to long day lengths. The length of the photoperiod that may be stimulatory can only be determined experimentally for each species, but it may range from 13 to 17 hours. Ideally, it would increase gradually. Many birds will become unresponsive to this stimulus after prolonged! light stimulation. Work at UC Davis showed that cockatiels became resistant after two clutches. For pet birds, the sometimes prolonged or erratic photoperiods that they are exposed to in the home may affect them behaviorally. A bird exhibiting signs of sexual over stimulation or frustration (such as plucking) may respond to a shortened day length.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass.
->answer: Light is part of the electromagnetic spectrum, which ranges from radio waves to gamma rays. Like sound, light is a wave. . And light is a transverse wave (like a water wave). For its value, light is used mainly for industry and homes but, light still has deeper uses in our life. Sunlight on daytime is light, without it, how can we have energy to supply our needs? As we know that SUNLIGHT POWERS ALL LIFE ON earth. Light can also be created as an anti-HIV effect of hypericin as this article say; The requirement for light in the anti-HIV-1 activity of hypericin was investigated. The hypericin concentration-dependence and light dosage-dependence of the reaction were measured. Under conditions in which hypericin caused substantial inactivation of HIV-1, there was a strict requirement for visible light. Only when the concentration of hypericin approached the cytotoxic level was there an apparent light-independent antiviral effect. This strict light-requirement for the antiviral effect could explain some of the apparently discrepant results reported by other workers. Furthermore if hypericin is contemplated for use in humans, the importance of light must be considered. Light can also be used as a cure. Acne, wrinkles, viruses and more can be treated with light. Researchers are exploring everything from penetrating beams of light that seem to repair heart tissue after a heart attack to "light therapy" that appears to improve Alzheimer's patients' ability to sleep through the night. Doctors are remedying the side effects of cancer treatments, severe acne and other ailments just by shining high-intensity light in varying colors on the affected area. Exploring the whole value of light may keep you face a monitor for a whole day. That's all for the first assignment! Thank you! *end*
>>>>>mAAUng GaBiE sA tanAn.......espEcIaLly ni mAam...
""ligh is also electromagnetic spectrum that made up of different speeds of wavelengths and include ultraviolet and infrared rays. There are several different kinds of electromagnetic waves that move at the speed of light. Many scientists worked to discover the actual speed of light.......
""After the discovery of infrared light by Herschel, a Danish physicist named Hans Christian Oersted found an electrical current that could change the direction of a compass' needle. André-Marie Ampère also found that different electrical currents could also attract or repel one another. It was in 1865 when James Clerk Maxwell proposed the idea of electromagnetism. He showed that electricity and magnetism were closely related and if made to surge back and forth, could produce alternating electromagnetic waves, which would move at the speed of light. Maxwell then concluded that light itself must be an electromagnetic wave.
Infrared, visible light, and ultraviolet are not the only types of waves. Further down past infrared lay microwaves, radar, television waves, and radio waves. Microwaves are thought to have been released during the Big Bang, which could have started the universe. These slow waves are used in microwave ovens to heat food by changing the alignment of water molecules. Even slower are radar waves. Radar is an acronym for "Radio Detection and Ranging." Radar scanners send out short radio waves and detect the echoes from objects in their path. Further down are television waves. These waves send out sound and pictures to our TV sets. The slowest known waves of all are radio waves. Not only produced by radio stations, radiowaves are sent out by stars and galaxies.
At the ultraviolet end of the spectrum are three other types of waves, all with higher frequencies than ultraviolet. Directly in front of ultraviolet is X-rays. While X-rays can pass through the soft parts of our bodies, they can not penetrate bone. This is why they are used today to take pictures of broken bones. Gamma rays are radioactive and are released by certain atomic nuclei. With their large amounts of energy they are able to penetrate metal and concrete and kill living cells. This type of wave is released by nuclear bombs, causing multitudes of destruction. The highest-energy and most frequent waves are cosmic rays. They are made up of particles of atomic nuclei, electrons, and gamma rays. The earth's atmosphere protects from these waves which come from outer space.
Though it may not seem like it, light takes time to get from one place to another. The light we see from the stars at night was emitted from the star a very long time ago. In fact, the star might have burned out by the time its rays reach us, but we can't see it because it takes times to reach our solar system.
The first clue towards the speed of light came from outer space, from the planet Jupiter. In 1676, Danish astronomer Olaus Roemer observed the difference in peroids that Jupiter's moons had to the Earth's orbit. He realized that the light reflected off the moons had a different amount of light to travel depending on the Earth's position. Using this knowledge, he used mathematics to estimate that the speed of light was 136,646 miles per second. Unfortunately, Roemer didn't know that his calculations were too low, but his work was a large accomplishment for his time.
Armand Fizeau made the first land-based estimate in 1849. Fizeau set up an experiment where he placed a light five and a half miles away from a mirror. In front of the light, he set up a wheel with toothed edges. When the light would shine, it would pass through the gap between two teeth. The mirror would reflect the beam back and would shine through the next gap between the teeth. Fizeau could then estimate the speed of light from the speed at which the toothed wheel was moving. He measured the speed at 194,410 miles per second.
A year later in 1850, Léon Foucault made some changes to Fizeau's experiment. Instead of using a toothed wheel, Foucault replaced it with a spinning mirror. The light would shine onto the spinning mirror and be reflected towards a series of stationary mirrors. By measuring the amount of distance the light had to travel and knowing how fast the mirror was spinning, Foucault figured the speed of light to be 185,093 miles per second. Foucault's results were very close to the actual speed of light.
Once lasers were invented, scientists were able to measure the speed of light much more easily. In 1972, the National Institute of Standards and Technology discovered that the actual speed of light was 299,792,458 meters per second, or 186,282 miles per second (just 189 miles different than Foucault's measurement). Because of these new results, the General Conference of Weights and Measures fixed the meter as the distance light travels in 1/299,792,458 of a second.
However, the speed of light does vary, depending on the medium. Albert Einstein proved that light is the fastest moving thing in a vacuum, with its speed being roughly 186,000 miles per second. In water, the speed of light slows to 140,000 miles per second. Its speed is 124,000 per second in glass. Through a diamond, the speed of light is 77,500 miles per second.
>>>>>mAAUng GaBiE sA tanAn.......espEcIaLly ni mAam...
""ligh is also electromagnetic spectrum that made up of different speeds of wavelengths and include ultraviolet and infrared rays. There are several different kinds of electromagnetic waves that move at the speed of light. Many scientists worked to discover the actual speed of light.......
""After the discovery of infrared light by Herschel, a Danish physicist named Hans Christian Oersted found an electrical current that could change the direction of a compass' needle. André-Marie Ampère also found that different electrical currents could also attract or repel one another. It was in 1865 when James Clerk Maxwell proposed the idea of electromagnetism. He showed that electricity and magnetism were closely related and if made to surge back and forth, could produce alternating electromagnetic waves, which would move at the speed of light. Maxwell then concluded that light itself must be an electromagnetic wave.
Infrared, visible light, and ultraviolet are not the only types of waves. Further down past infrared lay microwaves, radar, television waves, and radio waves. Microwaves are thought to have been released during the Big Bang, which could have started the universe. These slow waves are used in microwave ovens to heat food by changing the alignment of water molecules. Even slower are radar waves. Radar is an acronym for "Radio Detection and Ranging." Radar scanners send out short radio waves and detect the echoes from objects in their path. Further down are television waves. These waves send out sound and pictures to our TV sets. The slowest known waves of all are radio waves. Not only produced by radio stations, radiowaves are sent out by stars and galaxies.
At the ultraviolet end of the spectrum are three other types of waves, all with higher frequencies than ultraviolet. Directly in front of ultraviolet is X-rays. While X-rays can pass through the soft parts of our bodies, they can not penetrate bone. This is why they are used today to take pictures of broken bones. Gamma rays are radioactive and are released by certain atomic nuclei. With their large amounts of energy they are able to penetrate metal and concrete and kill living cells. This type of wave is released by nuclear bombs, causing multitudes of destruction. The highest-energy and most frequent waves are cosmic rays. They are made up of particles of atomic nuclei, electrons, and gamma rays. The earth's atmosphere protects from these waves which come from outer space.
Though it may not seem like it, light takes time to get from one place to another. The light we see from the stars at night was emitted from the star a very long time ago. In fact, the star might have burned out by the time its rays reach us, but we can't see it because it takes times to reach our solar system.
The first clue towards the speed of light came from outer space, from the planet Jupiter. In 1676, Danish astronomer Olaus Roemer observed the difference in peroids that Jupiter's moons had to the Earth's orbit. He realized that the light reflected off the moons had a different amount of light to travel depending on the Earth's position. Using this knowledge, he used mathematics to estimate that the speed of light was 136,646 miles per second. Unfortunately, Roemer didn't know that his calculations were too low, but his work was a large accomplishment for his time.
Armand Fizeau made the first land-based estimate in 1849. Fizeau set up an experiment where he placed a light five and a half miles away from a mirror. In front of the light, he set up a wheel with toothed edges. When the light would shine, it would pass through the gap between two teeth. The mirror would reflect the beam back and would shine through the next gap between the teeth. Fizeau could then estimate the speed of light from the speed at which the toothed wheel was moving. He measured the speed at 194,410 miles per second.
A year later in 1850, Léon Foucault made some changes to Fizeau's experiment. Instead of using a toothed wheel, Foucault replaced it with a spinning mirror. The light would shine onto the spinning mirror and be reflected towards a series of stationary mirrors. By measuring the amount of distance the light had to travel and knowing how fast the mirror was spinning, Foucault figured the speed of light to be 185,093 miles per second. Foucault's results were very close to the actual speed of light.
Once lasers were invented, scientists were able to measure the speed of light much more easily. In 1972, the National Institute of Standards and Technology discovered that the actual speed of light was 299,792,458 meters per second, or 186,282 miles per second (just 189 miles different than Foucault's measurement). Because of these new results, the General Conference of Weights and Measures fixed the meter as the distance light travels in 1/299,792,458 of a second.
However, the speed of light does vary, depending on the medium. Albert Einstein proved that light is the fastest moving thing in a vacuum, with its speed being roughly 186,000 miles per second. In water, the speed of light slows to 140,000 miles per second. Its speed is 124,000 per second in glass. Through a diamond, the speed of light is 77,500 miles per second.
SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light. Earth would not have any life on it without the Sun’s energy, which reaches Earth in the form of heat and light. This energy warms our days and illuminates our world. Green plants absorb sunlight and convert it to food, which these plants then use to live and grow. In this process, the plants give off the oxygen that animals breathe. Animals eat these plants for nourishment. All plant and animal life relies on the Sun’s presence. Light is also essential for the survival of most animal species. The Sun also provides—directly or indirectly—much of the energy on Earth that people use for fuel ( Solar Energy) Devices called solar cells turn sunlight into electricity. Sunlight can heat a gas or liquid, which can then be circulated through a building to heat the building. The energy stored in fossil fuels originally came from the Sun. Ancient plants used sunlight as fuel to grow. Animals consumed these plants. The plants and animals stored the energy of sunlight in the organic material that composed them. When the ancient plants and animals died and decayed, this organic material was buried and gradually turned into the petroleum, coal, and natural gas people use today. The Sun’s energy produces the winds and the movements of water that people harness to produce electricity (see Wind Energy; Water Power). The Sun heats Earth’s oceans and land, which in turn heat the air and make it circulate in the atmosphere as wind. The Sun fuels Earth’s water cycle, evaporating water from the oceans, seas, and lakes. This water returns to the ground in the form of precipitation, flowing back to the oceans through the ground and in rivers. The energy of water’s motion in rivers can be harnessed with dams..... LIGHT as medicine.,., Niels Ryberg Finsen (1860-1904), Danish physician and Nobel Prize winner who made important discoveries regarding the use of light waves in the treatment of disease. Finsen was born in Tórshavn, the capital of the Faeroe Islands, a part of Denmark located north of the British Isles. After completing his early schooling in Denmark and in Reykjavík, Iceland, Finsen attended the University of Copenhagen in Denmark, receiving his medical degree in 1891. He then taught anatomy in the university's Department of Surgery, leaving in 1893 to devote himself full-time to studying “phototherapy,” or the therapeutic effects of light. In 1896 he established the Light Institute in Copenhagen. For his groundbreaking contributions to the new field of phototherapy, Niels Finsen received the 1903 Nobel Prize in physiology or medicine. Even as a child, Finsen had been fascinated by the effects of sunlight on living things. His research as an undergraduate included experiments in which he observed how sunlight affected the tissue of insects, tadpoles, and other animals. Later Finsen decided to turn his efforts toward the treatment of human diseases. In 1893 he began to study the use of filtered sunlight in the treatment of skin lesions caused by smallpox, a viral disease. Red light—that is, light from the red end of the spectrum—with its harmful heat rays filtered out, proved successful in promoting the healing of smallpox lesions. After publishing key papers on phototherapy in 1893 and 1894, Finsen began research into the treatment of lupus vulgaris, a disfiguring skin disease caused by bacteria. Finsen had noted the findings of previous researchers, who discovered that light could kill bacteria. Focusing an artificial light through a prism, Finsen exposed diseased tissue to high concentrations of ultraviolet light. The method proved highly effective in treating lupus vulgaris. Finsen established his Light Institute in Copenhagen, where hundreds of lupus vulgaris patients were successfully treated over the next few years. The use of ultraviolet light remained the central treatment for lupus vulgaris for decades.
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WEB RESULTS[PDF] RE-300 Instruments and Development: An Evaluation of IDB Lending Modalities 471k - Adobe PDF - View as HTML VALUABILITY. S. CORES ON. S. ECTOR /PBL. OPERATIONS. A. NNEX. 14: F ... important in light of the potential moral hazard problems associated with lending ... www.iadb.org/ove/Documents/uploads/cache/591687.pdf Neccessary Poetry valuability is brought about. by defectiveness. and you'll get used to it ... you're the light i've been seeking. you were mind boggling. you were intense ... www.angelfire.com/oh3/neccessaryknight/poetry.html - Cached NASM Oral History Project, Webb #7 ... strengthened as test after test proved the valuability of the system. ... Apollo 11, and could then be judged in the light of the success of 2 landings. ... www.nasm.si.edu/research/dsh/TRANSCPT/WEBB7.HTM - 84k - Cached Lego nostalgia part 1 | nicjasno.com ... on peeron.com the ratio between and valuability of parts you get for the money ... The car will be a sports car, 2/3 the length of the challenger, and very light. ... www.nicjasno.com/node/973 - Cached VN Boards - Skald Report - Post 1.62 ... indicator by itself of the perceived valuability of this song, yet it is our ... PBT; Friars, light tanks and assassin classes have, among other things, high to ... vnboards.ign.com/message.asp?topic=51755749 - Cached [PDF] Introduction and Purposes 271k - Adobe PDF - View as HTML ... Resource Inherently Valuability Rating. 24. ... Normal light contains a range of wavelengths familiar to us as ... those that are reflected by visible light. ... califonborough-nj.org/files/.../ERI Narrative Issue 1.pdf The Beanie Baby Secondary Market ... limited amount of time, more valuability should eventually increase to the product. ... like wingless Quackers, Black Batty, Light Blue Peanut, and ty-dyed ... www.geocities.com/collectiblezz/SecondaryMarket.html - Cached PSP Crazy - Article: The History of Console Piracy and how it affects ... By Vahid Mirjamali (Owner of PSPcrazy.com) ... compare to the game satisfaction and valuability.If the game is really gud,i ... Grow up people and see the light... www.pspcrazy.com/?page=Articles&action=showarticle&id=201 - 220k - Cached [PDF] RE-288 Poverty Reduction and the IDB: An Evaluation of the Bank's ... 682k - Adobe PDF - View as HTML 21. VI. E. VALUABILITY .25. VII. R. ESULTS : O. PPORTUNITIES AND. C ... explicit poverty strategy in light of the controversial nature of the issue and the ... enet.iadb.org/idbdocswebservices/idbdocsInternet/...?docnum=320191 Personal approach to Symbolic reality ... within history, whole societal movements can be reflective of its light. ... The life pierced by call of death discovers valuability. ... www.crvp.org/seminar/05-seminar/Ekaterina.htm - Cached< Prev 1 2 3 4 5 6 7 8 9 10 Next >
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WEB RESULTS[PDF] RE-300 Instruments and Development: An Evaluation of IDB Lending Modalities 471k - Adobe PDF - View as HTML VALUABILITY. S. CORES ON. S. ECTOR /PBL. OPERATIONS. A. NNEX. 14: F ... important in light of the potential moral hazard problems associated with lending ... www.iadb.org/ove/Documents/uploads/cache/591687.pdf Neccessary Poetry valuability is brought about. by defectiveness. and you'll get used to it ... you're the light i've been seeking. you were mind boggling. you were intense ... www.angelfire.com/oh3/neccessaryknight/poetry.html - Cached NASM Oral History Project, Webb #7 ... strengthened as test after test proved the valuability of the system. ... Apollo 11, and could then be judged in the light of the success of 2 landings. ... www.nasm.si.edu/research/dsh/TRANSCPT/WEBB7.HTM - 84k - Cached Lego nostalgia part 1 | nicjasno.com ... on peeron.com the ratio between and valuability of parts you get for the money ... The car will be a sports car, 2/3 the length of the challenger, and very light. ... www.nicjasno.com/node/973 - Cached VN Boards - Skald Report - Post 1.62 ... indicator by itself of the perceived valuability of this song, yet it is our ... PBT; Friars, light tanks and assassin classes have, among other things, high to ... vnboards.ign.com/message.asp?topic=51755749 - Cached [PDF] Introduction and Purposes 271k - Adobe PDF - View as HTML ... Resource Inherently Valuability Rating. 24. ... Normal light contains a range of wavelengths familiar to us as ... those that are reflected by visible light. ... califonborough-nj.org/files/.../ERI Narrative Issue 1.pdf The Beanie Baby Secondary Market ... limited amount of time, more valuability should eventually increase to the product. ... like wingless Quackers, Black Batty, Light Blue Peanut, and ty-dyed ... www.geocities.com/collectiblezz/SecondaryMarket.html - Cached PSP Crazy - Article: The History of Console Piracy and how it affects ... By Vahid Mirjamali (Owner of PSPcrazy.com) ... compare to the game satisfaction and valuability.If the game is really gud,i ... Grow up people and see the light... www.pspcrazy.com/?page=Articles&action=showarticle&id=201 - 220k - Cached [PDF] RE-288 Poverty Reduction and the IDB: An Evaluation of the Bank's ... 682k - Adobe PDF - View as HTML 21. VI. E. VALUABILITY .25. VII. R. ESULTS : O. PPORTUNITIES AND. C ... explicit poverty strategy in light of the controversial nature of the issue and the ... enet.iadb.org/idbdocswebservices/idbdocsInternet/...?docnum=320191 Personal approach to Symbolic reality ... within history, whole societal movements can be reflective of its light. ... The life pierced by call of death discovers valuability. ... www.crvp.org/seminar/05-seminar/Ekaterina.htm - Cached< Prev 1 2 3 4 5 6 7 8 9 10 Next >
Upon the subject of the liturgical use of lights, as an adjunct of the services of the Church, something has already been said under such headings as ALTAR (IN LITURGY), sub-title Altar-Candles; BENEDICTION OF THE BLESSED SACRAMENT; CANDLES; CANDLESTICKS; LAMPS AND LAMPADARII. The present article will be concerned only with the more general aspect of the question, and in particular with the charge so often levelled against Catholicism of adopting wholesale the ceremonial practices of the pagan world.
How far the use of lights in the daytime as an adjunct of the Liturgy can be traced back to the second or third century A. D. is not quite easy to decide. On the one hand, there seems to be some evidence that the Christians themselves repudiated the practice. Although Tertullian ("Apol.", xlvi and xxxv; "De Idololat.", xv) does not make any direct reference to the use of lights in religious worship, still he speaks in strong terms of the uselessness of burning lamps in the daytime as an act of piety towards the emperors. This would be somewhat inconsistent, if the Christians themselves had been open to the same reproach. Moreover, several of the Fathers of the fourth century might seem to be more explicit in their condemnation of a display of lamps. For example, about the year 303, Lactantius writes: "They [the pagans] burn lights as to one dwelling in darkness. . . Is he to be thought in his right mind who offers for a gift the light of candles and wax tapers to the author and giver of light? . . . But their Gods, because they are of the earth, need light that they need not be in darkness" ("Institut. Div.", VI, ii). In like manner, St. Gregory of Nazianzus, towards the end of the same century, observes: "Let not our dwelling-place blaze with visible light and resound with minstrelsy, for this indeed is the custom of the Greek holy-month, but let us not honour God with these things and exalt the present season with unbecoming rites, but with purity of soul and cheerfulness of mind and with lamps which enlighten the whole body of the Church, i.e. with divine contemplations and thoughts" (Orat., v, 35). The rhetorical character of such passages makes it dangerous to draw inferences. It may well be that the writers are merely protesting against the illuminations which formed part of the ordinary religious cultus of the emperors, and wish to state forcibly the objections against a similar practice which was beginning to find favour among Christians. It is, at any rate certain that even earlier than this the liturgical use of lights must have been introduced. The decree of the Spanish Council of Illiberis, or Elvira (about A. D. 305), is too obscure to afford a firm basis for argument (see Hefele-Leclercq, "Hist. des Conciles", I, 212). Still this prohibition, "that candles be not lighted in a cemetery during the day, for the spirits of the saints ought not to be disquieted" (can. xxxiv), at least shows that the practice — which we know to have been long in use among pagans — of burning lights, for some symbolical or superstitious reason, even in the daytime, was being adopted among the Christians also. To discuss in detail the perplexing and seemingly inconsistent references of St. Jerome to the use of lights would not be possible here. But two facts stand out clearly:
(1) that he admitted the existence of a pretty general custom of burning candles and lamps in honour of the martyrs, a custom which he apologizes for without unreservedly approving it; and (2) that the saint, though he denies that there is any general practice among the Christians of burning lights during the daytime, still admits at least some instances of a purely liturgical use of light. Thus he says: "Apart from honouring the relics of martyrs, it is the custom, through all the Churches of the East, that when the gospels are to be read lights are kindled, though the sun is already shining, not, indeed, to dispel darkness, but to exhibit a token of joy . . . and that, under the figure of bodily light, that light may be set forth of which we read in the psalter 'thy word is a lamp to my feet and a light to my paths" (C. Vigilantium, vii). This testimony is particularly valuable because it so clearly refutes any exclusively utilitarian view of the use of lights in the churches.
From Eusebius, St. Paulinus of Nola, the "Peregrinatio Ætheriæ" (Pilgrimage of Ætheria), and other authorities, we have abundant evidence that the Christians of the fourth century, and probably earlier still, upon Easter eve and some other solemn festivals, made a great display of lamps and candles of all kinds. Moreover, this does not seem to have been confined to the nocturnal vigil itself, for St. Paulinus in describing the feast of St. Felix to whom his church was dedicated, tells us in verse how "the bright altars are crowned with lamps thickly set. Lights are burnt, odorous with waxed papyri. They shine by night and day; thus night is radiant with the brightness of the day, and the day itself, bright in heavenly beauty, shines yet more with light doubled by countless lamps" ("Poem.", xiv, "Nat." iii, in P. L., LXI, 467). Still this poetical language may very possibly mean no more than that in a rather dark church it was found desirable to keep the lamps burning even in daytime upon great festivals, when there was a large concourse of people. It tells us nothing of any use of lights which is liturgical in the stricter sense of the word. The same may be said of various references to the festal adornment of churches with lamps and candles which may be found in the writings of the Christian poet Prudentius (cf. P. L., LIX, 819, 829; and LX, 300). Still, when we find in the newly discovered "Testament of our Lord" (l. 19) an injunction regarding church buildings, that "all places should be lighted both for a type and also for reading", it seems clear that St. Jerome was not alone in attaching a mystical significance to the use of lights. Hence we may infer that before the days (about A. D. 475) of the liturgical homilist Narsai (see LAMPS AND LAMPADARII) the use of lamps and candles around the altar during the Liturgy had become universal.
It should be added that no great importance can be attached to the mention by St. Paulinus of Nola, of "a perpetual light" in the church ("continuum scyphus argenteus aptus ad usum"; cf. P. L., LXI, 539). This certainly cannot be assumed to have been intended as a mark of respect to the Blessed Sacrament reserved for the sick. In the days before the invention of matches the continuance of some source of fire from which a light could be readily obtained was a matter of great convenience. Such a perpetual light seems to have been usually kept up, then as now, in Jewish synagogues (cf. Exodus 27:20; Leviticus 24:2), but it was only the later Talmudists who discovered in this a purpose of honouring the Torah, or Books of the Law, preserved in the Ark. The same utilitarian design probably underlay any Christian practice, which, after all, is not very widely attested, of keeping a light perpetually burning in the church.
But to return to the liturgical use of lights in the stricter sense, there are not wanting many considerations to suggest that, despite the lack of direct evidence, this practice is probably of very much older date than the fourth century. To begin with, the seven-branched "candlestick", or more accurately lamp-stand, was a permanent element in the Temple ritual at Jerusalem and more than one Jewish festival (e.g. the Dedication feast and that of Tabernacles), was marked by a profuse use of lights. Moreover, the Apocalypse (i, 12; iv, 5; xi, 4), in the prominence which it gives to the mention of candlesticks and lamps, is probably only echoing the more or less liturgical conceptions already current at the time. Again, the fact that the Liturgy was at first no doubt celebrated in the evening (cf. 1 Corinthians 11:21), as also the necessity that the faithful should often assemble by stealth (as in the catacombs) or in the early hours of the morning (cf. Pliny, "Epp", X, n. 97 — ante lucem convenire; and Tertullian, "De Cor.", iii — antelucanis cœtibus), render it highly probable that artificial light must have come to be regarded as an ordinary adjunct of the Liturgy. Hence the use of lamps and candles was probably continued even when not actually needed, just as, in more modern days, the bishop's bugia, which in the beginning served an entirely practical purpose, has come in time to be purely ceremonial. It is also noteworthy that early representations of the Last Supper nearly always give prominence to the lamp, while something of the same kind obtains in the first rude sketches of Christian altars. In any case, lamps and chandeliers are conspicuous amongst the earliest recorded presents to churches (see the "Liber Pontificalis", ed. Duchesne, passim; and cf. the inventory of Cirta, A. D. 303, in Morcelli, "Africa Christiana", II, 183; and Beissel, "Bilder aus der altchrist. Kunst", 247).
Both in ancient and modern times, the reproach has been leveled against the Church that in her ceremonial use of lights she has taken over without scruple the sensuous and often idolatrous practices of paganism. For this charge there is very little real justification. To begin with, it must be evident that such simple elements as light, music, rich attire, processions, ablutions, and lustrations, flowers, unguents, incense, etc., belong, as it were, to the common stock of all ceremonial, whether religious or secular. If there is to be any solemnity of external worship at all it must include some at least of these things, and whether we turn to the polytheistic ritual of ancient Greece and Rome, or to the nations of the far East, or to the comparatively isolated civilizations of the aborigines of Mexico and Peru, human striving after impressiveness is found to manifest itself in very similar ways. A multiplicity of lights is always in some measure joyous and decorative, and it is a principle taught by everyday experience that marks of respect which are shown at first with a strictly utilitarian purpose are regarded in the end as only the more honorific if they are continued when they are plainly superfluous. Thus an escort of torches or candle-bearers, which is almost a necessity in the dark, and is a convenience in the twilight, becomes a formality indicative of ceremonious respect if maintained in the full light of day. Again, since the use of lights was so familiar to Jewish ritual, there is no sufficient ground for regarding the Christian Church as in this respect imitative either of the religions of Greece and Rome or of the more oriental Mithra worship. At the same time, it seems probable enough that certain features of Christian ceremonial were directly borrowed from Roman secular usages. For example, the later custom that seven acolytes with candlesticks should precede the pope, when he made his solemn entry into the church, is no doubt to be traced to a privilege which was common under the Empire of escorting the great functionaries of the State with torches. This right is expressly recognised in the "Notitia Dignitatum", but it may also be found in embryo at an earlier date, when the Consul Duilius for his victory over the Carthaginians, in the third century before Christ, obtained the privilege of being escorted home by a torch and a flute player. But granting, as even so conservative an historian as Cardinal Baronius is fully prepared to grant, a certain amount of direct borrowing of pagan usages, this is no subject of reproach to the Catholic Church. "What", he says, "is to prevent profane things, when sanctified by the word of God, being transferred to sacred purposes? Of such pagan rites laudably adopted for the service of the Christian religion we have many examples. And with regard more especially to lamps and candles, of which we are now speaking, who can reasonably find fault if those same things which were once offered to idols are now consecrated to the honour of the martyrs? If those lamps which were kindled in the temples on Saturdays — not as though the gods needed light, as even Seneca points out (Ep. xv, 66), but as a mark of veneration — are now lighted in the honour of the Mother of God? If the candles which were formerly distributed at the Saturnalia are now identified with the feast of the Purification of our Lady? What, I ask, is there so surprising if holy bishops have allowed certain customs firmly rooted among pagan peoples, and so tenaciously adhered to by them that even after their conversion to Christianity they could not be induced to surrender them, to be transferred to the worship of the true God?" (Baronius, "Annales", ad ann. 58, n. 77).
With regard to the use of lights in direct connexion with the Holy Sacrifice of the Mass, we find the whole system of portable lights elaborated in the earliest of the "Ordines Romani". Indeed, St. Jerome's plain reference, already quoted, to the carrying of lights at the Gospel, seems probably to take the practice back to at least three hundred years earlier, even if we may not appeal, as many authorities have done, to the words of the Acts of the Apostles (xx, 7-8): "And on the first day of the week, when we were assembled to break bread, Paul discoursed with them. . . . And there were a great number of lamps in the upper chamber where we were assembled." It does not seem to have been customary to place lights upon the altar itself before the eleventh century, but the "Ordines Romani" and other documents make it clear that, many centuries before this, lights were carried in procession by acolytes (see ACOLYTE), and set down upon the ground or held in the hand while Mass was being offered and the Gospel read. A decree of the so-called Fourth Council of Carthage directs that in the ordination of an acolyte a candlestick is to be given him, but this collection of canons does not belong, as was once supposed, to the year 398, but to the time of St. Cæsarius of Arles (about A. D. 512). A little later, i.e. in 636, St. Isidore of Seville (Etymol., VII, xii, n. 29) speaks quite explicitly on the point: "Acolytes", he says, "in Greek, are called Ceroferarii in Latin, from their carrying wax candles when the Gospel is to be read or the sacrifice to be offered. For then lights are kindled by them, and carried, not to drive away darkness, as the sun is shining, but for a sign of joy, that under the form of material light may be represented that Light of which we read in the Gospel: That was the true light." It was only at a later date that various synodal decrees required the lighting of first one candle, and afterwards of two, during the time of the celebration of Mass.
The use of lights in baptism, a survival of which still remains in the candle given to the catechumen, with the words: "Receive this burning light and keep thy baptism so as to be without blame", etc., is also of great antiquity. It is probably to be connected in a very immediate way with the solemnities of the Easter vigil, when the font was blessed, and when, after careful preparation and a long series of "scrutinies", the catechumens were at last admitted to the reception of the Sacrament. Dom Morin (Revue Bénédictine, VIII, 20; IX, 392) has given excellent reason for believing that the ceremonial of the paschal candle may be traced back to at least the year 382 in the lifetime of St. Jerome. Moreover the term photisthentes (illuminati), so constantly applied to the newly baptized in early writings, most probably bears some reference to the illumination which, as we know from many sources, marked the night of Holy Saturday. Thus St. Ambrose (De Laps. Virg., v, 19), speaking of this occasion, mentions "the blazing light of the neophytes", and St. Gregory of Nazianzus, in his great "Sermon on Holy Baptism", tells the candidates that "the lamps which you will kindle are a symbol of the illumination with which we shall meet the Bridegroom, with the lamps of our faith shining, not carelessly lulled to sleep" (Orat., xl, 46; cf. xlv, 2).
Again, the pagan use of lights at funerals seems to have been taken over by the Church as a harmless piece of ceremonial to which a Christian colour might easily be given. The early evidence upon this point in the writings of the Fathers is peculiarly abundant, beginning with what Eusebius tells us of the lying in state of the body of the Emperor Constantine: "They lighted candles on golden stands around it, and afforded a wonderful spectacle to the beholders, such as never was seen under the sun since the earth was made" (Vita. Const., iv, 66). Similarly, St. Jerome tells us of the obsequies of St. Paula in 386: "She was borne to the grave by the hands of bishops, who even put their shoulders under the bier, while other pontiffs carried lamps and candles before her" (Ad Eustoch., ep. cviii, n. 29). So, again in the West, at the funeral of St. Germanus of Auxerre, "The number of lights beat back the rays of the sun, and maintained their brightness even through the day" (Constantius, "Vita S. Germani", II, 24).
It is also certain that, from a very early period, lamps and candles were burnt around the bodies, and then, by a natural transition, before the relics, of the martyrs. How far this was merely a development of the use of lights in funerals, or how far it sprang from the earlier pagan custom of displaying a number of lamps as a tribute of honour to the emperor or others, it is not easy to decide. The practice, as we have seen, was known to St. Jerome, and is with some reservation defended by him. This burning of lights before shrines, relics, and statues naturally assumed great developments in the Middle Ages. Bequests to various "lights" in the churches which the testator desired to benefit generally occupy a considerable space in medieval wills, more particularly in England.
Upon the symbolism of ecclesiastical lights much has been written by medieval liturgists from Amalarius downwards. That all such lights typify Jesus Christ, Who is the Light of the World, is a matter of general agreement, while the older text of the "Exultet" rendered familiar the thought that the wax produced by virgin bees was a figure of the human body which Christ derived from His immaculate Mother. To this it was natural to add that the wick was emblematic of Christ's human soul, while the flame represented His Godhead. But the medieval liturgists also abound in a variety of other symbolic expositions, which naturally are not always quite consistent with one another.
Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
For diurnal species (species that are active during the day), light is important for many reasons. Obviously, it is required for vision, and most birds have highly developed sight. For many species of animals, full-spectrum light is required for the conversion of cholesterol to vitamin D. Light and its changing cycles -- photoperiodicity is used by animals to synchronize their biological clocks. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals.
Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom. The extremely large eye leaves little room in the head for anything else. For example. an ostrich eye is 2 inches in diameter, an owl eye is one-third the entire head weight, and the buzzard eye has four times the visual acuity (sharpness) of a human eye.
Photoperiodicity has long been studied in birds as a means of inducing reproduction. Day length is detected by the pineal gland. The adrenal gland is located in the brain between the cerebella hemispheres and the cerebellum. It has numerous functions, one of which is photoreceptor and regulator of circadian rhythms. Some photoreceptors are located deep within the brain and are not dependent upon the eyes for photoreception. The hormones of the pineal gland (melatonin primarily) affect sleep, behavior and brain electrical activity. There is also evidence that melatonin influences reproductive hormonal cycles by affecting the pituitary gland. This has been very important in inducing poultry to lay eggs and to maximize egg production.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
Numerous breeders of exotic birds have used changing the day length in an attempt to manipulate breeding. however, few controlled studies have been conducted to assess its effects. Work at the department of avian sciences at the University of California at Davis and elsewhere demonstrated that long day lengths stimulate reproductive activity in cockatiels and blossom-headed parakeets. In general. birds must be exposed to short day lengths (10 hours of light, 14 hours of dark). before they can respond to long day lengths. The length of the photoperiod that may be stimulatory can only be determined experimentally for each species, but it may range from 13 to 17 hours. Ideally, it would increase gradually. Many birds will become unresponsive to this stimulus after prolonged! light stimulation. Work at UC Davis showed that cockatiels became resistant after two clutches. For pet birds, the sometimes prolonged or erratic photoperiods that they are exposed to in the home may affect them behaviorally. A bird exhibiting signs of sexual over stimulation or frustration (such as plucking) may respond to a shortened day length.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass.
Vitamin D can be toxic, so be careful not to over supplement. Birds housed outdoors do not need supplemental vitamin D. Special Effects Light affects the health and well being of people and animals in numerous ways. Dr. John Ott did some of the pioneering studies in the 1960s and 1970s. He conducted numerous studies on the effects of light on plants and animals. He utilized time-lapse photography to demonstrate plant growth and the effects of limiting the photo spectrum. Working with fluorescent lights, such as cool white, daylight white. and warm white bulbs that were limited in spectrum, some plants would not flower properly. By using light filters to further limit the light spectrum he could produce signs suggestive of viral disease in plants. He conducted similar studies in mice and found that deprivation of part of the light spectrum could produce loss of fur, skin disease, curling and loss of the tail, and inflammation of the heart muscle (myocarditis). It also affected the behavior of the mice, making some aggressive and agitated. In studies of children in school where curtains were closed and limited spectrum fluorescent lights were used, children were hyperactive and inattentive. This behavior was corrected when the lights were changed and the curtains were opened. He also equated malillumination with malnutrition.
A recent Wall Street Journal report showed how light is being used to enhance human well being. Prior to the invention of the electric light in 1879, buildings were designed with an emphasis on placement of windows to enhance natural lighting. As architects relied more on electric lighting, natural lighting of buildings was reduced. The need for energy efficiency has again affected how we design our indoor spaces for light. Recently, European countries have begun to require that a percentage of a building's light come from outdoors -- 37 percent in the Netherlands, for example.
According to a report by the Rocky Mountain Institute in Snowmass, Colorado, increasing daylight results in fewer days lost to absenteeism and fewer errors and defects. The report, "Greening the Building and the Bottom Line", cites improved heating and cooling in eight commercial buildings thanks to natural light. Installation of special skylights and-tall windows improved lighting and cut lighting costs by up to 75 percent. An unexpected effect was a 15-percent drop in employee absenteeism, as well as increased productivity and sales.
People living in northern cities that are overcast for long periods of time and receive little sunshine typically report depression. Birds housed continually indoors may also suffer from depression. Taking your wing-clipped bird outdoors for a bath in the sun is great for its plumage and its spirits. If you have the opportunity to see the plumage quality of birds housed outdoors that has access to rain and sunlight, you will be a believer.
Try to place your bird near a sunny window, but make sure it can move out of direct sunlight when it wants. A useful substitute may be a full-spectrum fluorescent bulb with the fixture close enough to the bird to provide the UV spectrum. Ideally, the bulb should be within a foot or two of the bird to provide benefits.
Remember that the capability of the bulb to produce UV does not last for the life of the bulb. The bulb can still be used for general lighting purposes after it is no longer producing full-spectrum light. Certainly, we must not forget the potential hazard of excessive UV exposure, such a skin cancer and eye disease.®
Lighting includes both artificial light sources such as lamps and natural illumination of interiors from daylight. Lighting represents a major component of energy consumption, accounting for a significant part of all energy consumed worldwide. Artificial lighting is most commonly provided today by electric lights, but gas lighting, candles or oil lamps were used in the past, and still are used in certain situations. Proper lighting can enhance task performance or aesthetics, while there can be energy wastage and adverse health effects of lighting. Indoor lighting is a form of fixture or furnishing, and a key part of interior design. Lighting can also be an intrinsic component of landscaping.
Low-intensity lighting and haze in a concert hall allows laser effects to be visibleContents [hide] 1 Fixtures 1.1 Types 1.2 Methods 2 Vehicle use 3 Lamps 4 Design 5 Measurement 6 Energy consumption 7 Health effects 8 Environmental issues 9 Military use 10 Professional organizations 11 See also 11.1 Inventors 11.2 Lists 12 References 13 External links
Light, or visible light, is electromagnetic radiation of a wavelength that is visible to the human eye (about 400–700 nm). In a scientific context, the word light is sometimes used to refer to the entire electromagnetic spectrum. Moreover, in optics, the term "visible light" refers to electromagnetic radiation with wavelengths of ~300 nm (near UV) through ~1400 nm (near infrared). [1] Light is composed of elementary particles called photons.
Three primary properties of light are:
Intensity; Frequency or wavelength and; Polarization. Light can exhibit properties of both waves and particles. This property is referred to as wave–particle duality. The study of light, known as optics, is an important research area in modern physics.
Contents [hide] 1 Speed of light 2 Refraction 3 Optics 4 Light sources 5 Theories about light 5.1 Indian theories 5.2 Greek and Hellenistic theories 5.3 Optical theory 5.4 The 'plenum' 5.5 Particle theory 5.6 Wave theory 5.7 Electromagnetic theory 5.8 The special theory of relativity 5.9 Particle theory revisited 5.10 Quantum theory 5.11 Wave–particle duality 5.12 Quantum electrodynamics 6 Light pressure 7 Spirituality 8 References 9 See also 10 External links
The quality of light is important but also the quantity and the length are. For the quality, the visible to human-eye light spectrum is composed of all the seven (7) rainbow colors. But the main colors are red, green and blue. Those useful to plants are blue and red spectrum. The quantity refers too how much light is present and the length refers to the time of exposition to light.
The blue spectrum of light will interact with the plant by inducing foliage composition and creating a dense plant. The red spectrum will induce growth but also flowering. The role of the green spectrum with plants is undetermined. The best source of light is still free, because it is the sun. The sun produces an almost equal amount of red, green and blue rays.
Two phenomena are also associated with plant and light. They are called phototropism and photoperiodism. The first one can be observe on sunflowers. Sunflower will turn wherever the sun is. They are not searching for the sun, but the best source of light.
The last of the phenomena, photoperiodism, is how the plants react to the cycle of day and night, presence of light and lack of light. The successive periods are in direct link with the seasons. Amount of light and day lentgh vary with the seasons, so in fall when temperature drop and day are getting shorter, leaves are dropping and plants will go dormant. The contrary is happening in spring when days are getting longer and temperature increases, plants goes out of dormancy and activate its development. Playing with this phenomenon is a technique used by flowers producers. They induce flowering at a certain period of the year, like Easter or Christmas by giving no more then 8-9 hours of sunlight per day. To induce the flowering, they gradually bring back the exposition to light to an average of 12-16 hours of light a day. Of course this can be used on flowering bonsai tree.As we see, light is the main actor in plants development. But aside the technical side of things, what about direct effect of light or lack of light on our bonsai? Some plants are less demanding in term of light, but tree, hence bonsai, will require all the light they can get.
First, in situation of lack of light, the plant will react by producing a “leggy” plant. Leggy plants are those with long internodes on the trunk and branches. This is a result of plants trying to reach the light above the canopy of what it think is a shade create by taller tree’s. We don’t want this to happen to our miniature tree.
Light is essential to maintaining normal, healthy physiology. Exposure to sunrise is key to synchronizing our internal body cycles to the external world (so we sleep when it is dark and are alert during the day).
Modern industrial society began to tamper with this system, though. The loss of natural light - in dark apartments, in the workplace, on shift work, etc. - creates a state of light deprivation, making us vulnerable to depressed mood, sleep problems, fatigue, ability to concentrate, and more. Nature, too, posed a new problem when humans began to migrate north, where winter nights are long and dark.
Light levels as measured in lux vary greatly between indoor and outdoor lighting. You can see from the chart below how easy it is to become light deprived in our modern, indoor society.
Indoor Lighting Indoors at home 200-500 lux Indoors at office 400-700 lux Springtime Lighting on a Clear Day 5:55 Sunrise 750 lux 6:10 a.m. 2,500 lux 6:20 a.m. 5,000 lux 6:40 a.m. 10,000 lux 12:00 Noon 81,000 lux 5:10 p.m. 10,000 lux 5:30 p.m. 5,000 lux 5:40 p.m. 2,500 lux 5:55 Sunset 750 lux
Although researchers do not have firm numbers, a lot of people are light deprived. Symptoms of light deprivation include:
Feeling depressed or moody during the fall and winter Fatigue, lack of energy, and difficulty getting up in the morning Problems getting things done (lack of motivation) Reduced social contact (often reduced sexual interest) Cravings for carbohydrates and weight gain Surveys suggest that as many as 1 in 20 people experience full-blown winter depression in the northern hemisphere, and three times as many experience winter doldrums. Far larger numbers experience nonseasonal depression at some point in their lives, often for years at a time. With the recent findings that light therapy can also work for nonseasonal depression - light itself or in combination with drugs, the size of the responsive population multiplies.
Light is valuabe. yes!Light is valuable, because light is a universal substance that God used to create both the spiritual and the material world. Modern science has revealed that the material universe is made from energy. Light is one form of energy, and all energy is vibration. Without light, there would be no sight. The visual ability of humans and other animals is the result of the complex interaction of light, eyes and brain. We are able to see because light from an object can move through space and reach our eyes. Once light reaches our eyes, signals are sent to our brain, and our brain deciphers the information in order to detect the appearance, location and movement of the objects we are sighting at. The whole process, as complex as it is, would not be possible if it were not for the presence of light. Without light, there would be no sight. Are you somewhere inside a home? Look around. Wherever you are, there is at least one element whose presence can unfailingly be predicted. Light. There must be a window or a light fixture. The room is useless without light. When a room strikes you as pleasant to sit in, beautiful to look at, or efficient to work in, be attentive to its lighting. The placement and size of windows, or the type, position, and brightness of light fixtures, combine to create a certain mood, an atmosphere. Human beings are very sensitive to light: we easily perceive the impact that relatively small changes in lighting have on the overall feel of a room.
Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
For diurnal species (species that are active during the day), light is important for many reasons. Obviously, it is required for vision, and most birds have highly developed sight. For many species of animals, full-spectrum light is required for the conversion of cholesterol to vitamin D. Light and its changing cycles -- photoperiodicity is used by animals to synchronize their biological clocks. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals.
Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom. The extremely large eye leaves little room in the head for anything else. For example. an ostrich eye is 2 inches in diameter, an owl eye is one-third the entire head weight, and the buzzard eye has four times the visual acuity (sharpness) of a human eye.
Photoperiodicity has long been studied in birds as a means of inducing reproduction. Day length is detected by the pineal gland. The adrenal gland is located in the brain between the cerebella hemispheres and the cerebellum. It has numerous functions, one of which is photoreceptor and regulator of circadian rhythms. Some photoreceptors are located deep within the brain and are not dependent upon the eyes for photoreception. The hormones of the pineal gland (melatonin primarily) affect sleep, behavior and brain electrical activity. There is also evidence that melatonin influences reproductive hormonal cycles by affecting the pituitary gland. This has been very important in inducing poultry to lay eggs and to maximize egg production.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
Numerous breeders of exotic birds have used changing the day length in an attempt to manipulate breeding. however, few controlled studies have been conducted to assess its effects. Work at the department of avian sciences at the University of California at Davis and elsewhere demonstrated that long day lengths stimulate reproductive activity in cockatiels and blossom-headed parakeets. In general. birds must be exposed to short day lengths (10 hours of light, 14 hours of dark). before they can respond to long day lengths. The length of the photoperiod that may be stimulatory can only be determined experimentally for each species, but it may range from 13 to 17 hours. Ideally, it would increase gradually. Many birds will become unresponsive to this stimulus after prolonged! light stimulation. Work at UC Davis showed that cockatiels became resistant after two clutches. For pet birds, the sometimes prolonged or erratic photoperiods that they are exposed to in the home may affect them behaviorally. A bird exhibiting signs of sexual over stimulation or frustration (such as plucking) may respond to a shortened day length.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass.
Yes, LIGHT is valuable because it's the reason why we people recognize the beatiful surrounding that surrounds us. We also need light specially at night time, coz without light our world turns to be darker than ever. And mostly, we can't see without light. Light also give energy for us human and plants which we intend to use. ...hAiL!!, +mp678!!!.,
Yes, light is very important because of the kight, we can see our surroundings and also the image of the human. Light is very useful also in plants because without light, i think the plants can't produce their own food. We know that light came from the sun and without light, the earth will be in eternal darkness.
Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
For diurnal species (species that are active during the day), light is important for many reasons. Obviously, it is required for vision, and most birds have highly developed sight. For many species of animals, full-spectrum light is required for the conversion of cholesterol to vitamin D. Light and its changing cycles -- photoperiodicity is used by animals to synchronize their biological clocks. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals.
Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom. The extremely large eye leaves little room in the head for anything else. For example. an ostrich eye is 2 inches in diameter, an owl eye is one-third the entire head weight, and the buzzard eye has four times the visual acuity (sharpness) of a human eye.
Photoperiodicity has long been studied in birds as a means of inducing reproduction. Day length is detected by the pineal gland. The adrenal gland is located in the brain between the cerebella hemispheres and the cerebellum. It has numerous functions, one of which is photoreceptor and regulator of circadian rhythms. Some photoreceptors are located deep within the brain and are not dependent upon the eyes for photoreception. The hormones of the pineal gland (melatonin primarily) affect sleep, behavior and brain electrical activity. There is also evidence that melatonin influences reproductive hormonal cycles by affecting the pituitary gland. This has been very important in inducing poultry to lay eggs and to maximize egg production.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
Numerous breeders of exotic birds have used changing the day length in an attempt to manipulate breeding. however, few controlled studies have been conducted to assess its effects. Work at the department of avian sciences at the University of California at Davis and elsewhere demonstrated that long day lengths stimulate reproductive activity in cockatiels and blossom-headed parakeets. In general. birds must be exposed to short day lengths (10 hours of light, 14 hours of dark). before they can respond to long day lengths. The length of the photoperiod that may be stimulatory can only be determined experimentally for each species, but it may range from 13 to 17 hours. Ideally, it would increase gradually. Many birds will become unresponsive to this stimulus after prolonged! light stimulation. Work at UC Davis showed that cockatiels became resistant after two clutches. For pet birds, the sometimes prolonged or erratic photoperiods that they are exposed to in the home may affect them behaviorally. A bird exhibiting signs of sexual over stimulation or frustration (such as plucking) may respond to a shortened day length.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass.
Vitamin D can be toxic, so be careful not to over supplement. Birds housed outdoors do not need supplemental vitamin D. Special Effects Light affects the health and well being of people and animals in numerous ways. Dr. John Ott did some of the pioneering studies in the 1960s and 1970s. He conducted numerous studies on the effects of light on plants and animals. He utilized time-lapse photography to demonstrate plant growth and the effects of limiting the photo spectrum. Working with fluorescent lights, such as cool white, daylight white. and warm white bulbs that were limited in spectrum, some plants would not flower properly. By using light filters to further limit the light spectrum he could produce signs suggestive of viral disease in plants. He conducted similar studies in mice and found that deprivation of part of the light spectrum could produce loss of fur, skin disease, curling and loss of the tail, and inflammation of the heart muscle (myocarditis). It also affected the behavior of the mice, making some aggressive and agitated. In studies of children in school where curtains were closed and limited spectrum fluorescent lights were used, children were hyperactive and inattentive. This behavior was corrected when the lights were changed and the curtains were opened. He also equated malillumination with malnutrition.
A recent Wall Street Journal report showed how light is being used to enhance human well being. Prior to the invention of the electric light in 1879, buildings were designed with an emphasis on placement of windows to enhance natural lighting. As architects relied more on electric lighting, natural lighting of buildings was reduced. The need for energy efficiency has again affected how we design our indoor spaces for light. Recently, European countries have begun to require that a percentage of a building's light come from outdoors -- 37 percent in the Netherlands, for example.
According to a report by the Rocky Mountain Institute in Snowmass, Colorado, increasing daylight results in fewer days lost to absenteeism and fewer errors and defects. The report, "Greening the Building and the Bottom Line", cites improved heating and cooling in eight commercial buildings thanks to natural light. Installation of special skylights and-tall windows improved lighting and cut lighting costs by up to 75 percent. An unexpected effect was a 15-percent drop in employee absenteeism, as well as increased productivity and sales.
People living in northern cities that are overcast for long periods of time and receive little sunshine typically report depression. Birds housed continually indoors may also suffer from depression. Taking your wing-clipped bird outdoors for a bath in the sun is great for its plumage and its spirits. If you have the opportunity to see the plumage quality of birds housed outdoors that has access to rain and sunlight, you will be a believer.
Try to place your bird near a sunny window, but make sure it can move out of direct sunlight when it wants. A useful substitute may be a full-spectrum fluorescent bulb with the fixture close enough to the bird to provide the UV spectrum. Ideally, the bulb should be within a foot or two of the bird to provide benefits.
Remember that the capability of the bulb to produce UV does not last for the life of the bulb. The bulb can still be used for general lighting purposes after it is no longer producing full-spectrum light. Certainly, we must not forget the potential hazard of excessive UV exposure, such a skin cancer and eye disease.®
Bird Talk Magazine by Susan L. Clubb, D.V.M., DIP., AVBP - March 1996
All animals are dependent on light to some extent, but birds are particularly sensitive to it. Birds deprived of sunlight may develop a variety of problems, including poor nutrient absorption, vitamin D deficiency, feather plucking, and disruption of mating and breeding patterns.
Many bird owners place their pet's cage near a window or other light source, but that may not be enough to cure the problem, since glass can act as a filter, reflecting instead of transmitting certain portions of the spectrum.
Dr. John Ott's research into the light needs of people, plants and animals led to the invention of full-spectrum lighting, a term coined by Ott. Full-spectrum lighting recreates the light-environment birds and others have in the wild. The poultry industry has already discovered that the benefits of providing full-spectrum lighting include increased egg production, larger eggs with stronger shells, and healthier birds. Couldn't your bird benefit?
Pet bird keepers know that their companions need fresh air, proper foods and a constant supply of clean water in order to survive and thrive. But not everyone knows that birds need light, as well, for optimum health. Larges suppliers of Proper Lighting for birds are listed here:
Warning: Lighting: You may not be getting what you think you're buying.
Any incandescent bulb is fine for heat (for night time, you want dark light, such as the Nocturnal Light by Energy Savers Unlimited or a ceramic heating element). The technology (tungsten filament vs. the gases and coatings used in fluorescents) doesn't produce UVB, and only marginal UVA (which are the wavelengths in between UVB and visible light).
"Full spectrum" is a term used rather loosely. It can mean "produces UVB, UVA, visible light and infrared [the wavelengths longer than those in the spectrum we can see {visible light}] but the reality is that manufacturers of incandescents are calling their bulbs "full spectrum" to lull people into thinking they are getting UVB (and thus buying their product) when they are not. Incandescents are fine to use alone for room lighting, but birds require UVB. Also, birds from more northerly climates or colder temperature climates that do well with minimal UVB obtained from occasional exposure to natural sun thru windows, must have lighting used in conjunction with a UVB-producing fluorescents or lamps (not all fluorescents produce UVB or enough of it to do any good).
What's the difference between a WIDE Spectrum and a FULL Spectrum light?
Ahhhh....welcome to the Madison Avenue and the non-regulated pet product industry where accuracy never gets in the way of making product claims! Because there are no truth-in-advertising regulations covering pet products, manufactures can be as misleading as they like.
It used to be that 'full spectrum' lighting meant lights which produced both ultraviolet B, ultraviolet A and the full visible spectrum as well infrared heat. Once incandescent manufacturers figured out that people were being told to look for 'full spectrum' lighting, they started to market their wide spectrum (producing some, but not all of the visible wavelengths and no ultraviolet wavelengths) lights with 'full spectrum' in the ads and on packaging. Thus people are buying Chromalux, NeoWhite and "Full Spectrum" incandescent lights thought, incorrectly, that they are providing UVB, UVA and full visible wavelengths to their birds. In fact, incandescents are just producing, if they are putting out bright white light, only the visible spectrum; some which produce colored light, are not necessarily even producing the full visible spectrum, being corrected to increase or reduce certain parts of that spectrum.
->answer: Natural light is so important that we would fail to thrive without it. In fact, artists and those in the know spend thousands of dollars ensuring that they have natural light — and plenty of it — in their homes and workspaces. If you are tired, sluggish, depressed, and altogether unsatisfied with your home or your workspace, one of the first things to suspect is a lack of adequate lighting. Take a good look around your workspace or your living environment. Are there big windows in the rooms where you spend a large amount of time? Are there adequate numbers of windows which give natural light as well as fresh air? In the room where you sleep, is there a large window that provides natural light as well as fresh air in the morning? This is especially important, since you will have a hard time waking up in a room that is dark in the morning, and you will have a hard time getting good sleep in a room with small windows that provide poor ventilation.
Start becoming aware of the light in the rooms where you work and relax. If you are in a dingy, dark room, it will be very hard for you to be productive at work. It will also be difficult for you to feel alert and well. Similarly, it will be hard for you to relax and rest in a room with small windows.
Large windows that let in natural light make working or just relaxing far more enjoyable. Large windows let you look out at the beauty of nature and allow you to watch the world go by. Far from being distracting, they can allow you to have the lighting you need in order to do your work without ruining your eyes. Natural lighting can be one of the best light sources to work by. Large windows that let in lots of light will also allow you to achieve a better communication between exterior world and interior world. You feel more connected with your overall environment less isolated if you have adequate windows. Of course, natural light will also ensure that you get adequate of vitamin D, which is very important to your overall health. When you spend a lot of time in dark rooms, you look pasty and you don’t feel at your best. If you are busy and do not always get to spend plenty of time outdoors, you especially need to ensure that your windows let in as much natural sunlight as possible.
If your windows are small, dark, or don’t let in enough light, consider getting renovations. Although it may seem extreme, the cost, time, and effort of renovations when it comes to windows is well worth it. Not only can good windows save your eyesight, but they can also ensure that you are as receptive, happy, and healthy as possible. Look online for inexpensive windows solutions, and be sure to read all about all the window options available today. From vinyl windows to old-fashioned wooden frames, you’re sure to find a natural lighting solution that suits your style and your budget. While shopping, be sure to pick out some pretty blinds and curtains that will help you enjoy your new windows and your new outlook on life.
->answer: Natural light is so important that we would fail to thrive without it. In fact, artists and those in the know spend thousands of dollars ensuring that they have natural light — and plenty of it — in their homes and workspaces. If you are tired, sluggish, depressed, and altogether unsatisfied with your home or your workspace, one of the first things to suspect is a lack of adequate lighting. Take a good look around your workspace or your living environment. Are there big windows in the rooms where you spend a large amount of time? Are there adequate numbers of windows which give natural light as well as fresh air? In the room where you sleep, is there a large window that provides natural light as well as fresh air in the morning? This is especially important, since you will have a hard time waking up in a room that is dark in the morning, and you will have a hard time getting good sleep in a room with small windows that provide poor ventilation.
Start becoming aware of the light in the rooms where you work and relax. If you are in a dingy, dark room, it will be very hard for you to be productive at work. It will also be difficult for you to feel alert and well. Similarly, it will be hard for you to relax and rest in a room with small windows.
Large windows that let in natural light make working or just relaxing far more enjoyable. Large windows let you look out at the beauty of nature and allow you to watch the world go by. Far from being distracting, they can allow you to have the lighting you need in order to do your work without ruining your eyes. Natural lighting can be one of the best light sources to work by. Large windows that let in lots of light will also allow you to achieve a better communication between exterior world and interior world. You feel more connected with your overall environment less isolated if you have adequate windows. Of course, natural light will also ensure that you get adequate of vitamin D, which is very important to your overall health. When you spend a lot of time in dark rooms, you look pasty and you don’t feel at your best. If you are busy and do not always get to spend plenty of time outdoors, you especially need to ensure that your windows let in as much natural sunlight as possible.
If your windows are small, dark, or don’t let in enough light, consider getting renovations. Although it may seem extreme, the cost, time, and effort of renovations when it comes to windows is well worth it. Not only can good windows save your eyesight, but they can also ensure that you are as receptive, happy, and healthy as possible. Look online for inexpensive windows solutions, and be sure to read all about all the window options available today. From vinyl windows to old-fashioned wooden frames, you’re sure to find a natural lighting solution that suits your style and your budget. While shopping, be sure to pick out some pretty blinds and curtains that will help you enjoy your new windows and your new outlook on life.
->answer: Natural light is so important that we would fail to thrive without it. In fact, artists and those in the know spend thousands of dollars ensuring that they have natural light — and plenty of it — in their homes and workspaces. If you are tired, sluggish, depressed, and altogether unsatisfied with your home or your workspace, one of the first things to suspect is a lack of adequate lighting. Take a good look around your workspace or your living environment. Are there big windows in the rooms where you spend a large amount of time? Are there adequate numbers of windows which give natural light as well as fresh air? In the room where you sleep, is there a large window that provides natural light as well as fresh air in the morning? This is especially important, since you will have a hard time waking up in a room that is dark in the morning, and you will have a hard time getting good sleep in a room with small windows that provide poor ventilation.
Start becoming aware of the light in the rooms where you work and relax. If you are in a dingy, dark room, it will be very hard for you to be productive at work. It will also be difficult for you to feel alert and well. Similarly, it will be hard for you to relax and rest in a room with small windows.
Large windows that let in natural light make working or just relaxing far more enjoyable. Large windows let you look out at the beauty of nature and allow you to watch the world go by. Far from being distracting, they can allow you to have the lighting you need in order to do your work without ruining your eyes. Natural lighting can be one of the best light sources to work by. Large windows that let in lots of light will also allow you to achieve a better communication between exterior world and interior world. You feel more connected with your overall environment less isolated if you have adequate windows. Of course, natural light will also ensure that you get adequate of vitamin D, which is very important to your overall health. When you spend a lot of time in dark rooms, you look pasty and you don’t feel at your best. If you are busy and do not always get to spend plenty of time outdoors, you especially need to ensure that your windows let in as much natural sunlight as possible.
If your windows are small, dark, or don’t let in enough light, consider getting renovations. Although it may seem extreme, the cost, time, and effort of renovations when it comes to windows is well worth it. Not only can good windows save your eyesight, but they can also ensure that you are as receptive, happy, and healthy as possible. Look online for inexpensive windows solutions, and be sure to read all about all the window options available today. From vinyl windows to old-fashioned wooden frames, you’re sure to find a natural lighting solution that suits your style and your budget. While shopping, be sure to pick out some pretty blinds and curtains that will help you enjoy your new windows and your new outlook on life.
Light is essential to maintaining normal, healthy physiology. Exposure to sunrise is key to synchronizing our internal body cycles to the external world (so we sleep when it is dark and are alert during the day).
Modern industrial society began to tamper with this system, though. The loss of natural light - in dark apartments, in the workplace, on shift work, etc. - creates a state of light deprivation, making us vulnerable to depressed mood, sleep problems, fatigue, ability to concentrate, and more. Nature, too, posed a new problem when humans began to migrate north, where winter nights are long and dark.
Light levels as measured in lux vary greatly between indoor and outdoor lighting. You can see from the chart below how easy it is to become light deprived in our modern, indoor society.
Light is essential to maintaining normal, healthy physiology. Exposure to sunrise is key to synchronizing our internal body cycles to the external world (so we sleep when it is dark and are alert during the day).
Modern industrial society began to tamper with this system, though. The loss of natural light - in dark apartments, in the workplace, on shift work, etc. - creates a state of light deprivation, making us vulnerable to depressed mood, sleep problems, fatigue, ability to concentrate, and more. Nature, too, posed a new problem when humans began to migrate north, where winter nights are long and dark.
Light levels as measured in lux vary greatly between indoor and outdoor lighting. You can see from the chart below how easy it is to become light deprived in our modern, indoor society.
Light is essential to maintaining normal, healthy physiology. Exposure to sunrise is key to synchronizing our internal body cycles to the external world (so we sleep when it is dark and are alert during the day).
Modern industrial society began to tamper with this system, though. The loss of natural light - in dark apartments, in the workplace, on shift work, etc. - creates a state of light deprivation, making us vulnerable to depressed mood, sleep problems, fatigue, ability to concentrate, and more. Nature, too, posed a new problem when humans began to migrate north, where winter nights are long and dark.
Light levels as measured in lux vary greatly between indoor and outdoor lighting. You can see from the chart below how easy it is to become light deprived in our modern, indoor society.
->answer: The bottom line is: without light, there would be no sight. The visual ability of humans and other animals is the result of the complex interaction of light, eyes and brain. We are able to see because light from an object can move through space and reach our eyes. Once light reaches our eyes, signals are sent to our brain, and our brain deciphers the information in order to detect the appearance, location and movement of the objects we are sighting at. The whole process, as complex as it is, would not be possible if it were not for the presence of light. Without light, there would be no sight.
If you were to turn off the room lights for a moment and then cover all the windows with black construction paper to prevent any entry of light into the room, then you would notice that nothing in the room would be visible. There would be objects present that were capable of being seen. There would be eyes present which would be capable of detecting light from those objects. There would be a brain present which would be capable of deciphering the information sent to it. But there would be no light! The room and everything in it would look black. The appearance of black is merely a sign of the absence of light. When a room full of objects (or a table, a shirt or a sky) looks black, then the objects are not generating nor reflecting light to your eyes. And without light, there would be no sight.
The objects which we see can be placed into one of two categories: luminous objects and illuminated objects. Luminous objects are objects which generate their own light. Illuminated objects are objects which are capable of reflecting light to our eyes. The sun is an example of a luminous object, while the moon is an illuminated object. During the day, the sun generates sufficient light to illuminate objects on Earth. The blue skies, the white clouds, the green grass, the colored leaves of fall, the neighbor's house, and the car approaching the intersection are all seen as a result of light from the sun (the luminous object) reflecting off the illuminated objects and traveling to our eyes. Without the light from the luminous objects, these illuminated objects would not be seen. During the evening when the Earth has rotated to a position where the light from the sun can no longer reach our part of the Earth (due to its inability to bend around the spherical shape of the Earth), objects on Earth appear black (or at least so dark that we could say they are nearly black). In the absence of a porch light or a street light, the neighbor's house can no longer be seen; the grass is no longer green, but rather black; the leaves on the trees are dark; and were it not for the headlights of the car, it would not be seen approaching the intersection. Without luminous objects generating light which propagates through space to illuminate non-luminous objects, those non-luminous objects cannot bee seen. Without light, there would be no sight.
A common Physics demonstration involves the directing of a laser beam across the room. With the room lights off, the laser is turned on and its beam is directed towards a plane mirror. The presence of the light beam cannot be detected as it travels towards the mirror. Furthermore, the light beam cannot be detected after reflecting off the mirror and traveling through the air towards a wall in the room. The only locations where the presence of the light beam can be detected are at the location where the light beam strikes the mirror and at the location where the light beam strikes a wall. At these two locations, a portion of the light in the beam is reflecting off the objects (the mirror and the wall) and traveling towards the students' eyes. And since the detection of objects is dependent upon light traveling from that object to the eye, these are the only two locations where one can detect the light beam. But in between the laser and the mirror, the light beam cannot be detected. There is nothing present in the region between the laser and the mirror which is capable of reflecting the light of the beam to students' eyes.
->answer: The bottom line is: without light, there would be no sight. The visual ability of humans and other animals is the result of the complex interaction of light, eyes and brain. We are able to see because light from an object can move through space and reach our eyes. Once light reaches our eyes, signals are sent to our brain, and our brain deciphers the information in order to detect the appearance, location and movement of the objects we are sighting at. The whole process, as complex as it is, would not be possible if it were not for the presence of light. Without light, there would be no sight.
If you were to turn off the room lights for a moment and then cover all the windows with black construction paper to prevent any entry of light into the room, then you would notice that nothing in the room would be visible. There would be objects present that were capable of being seen. There would be eyes present which would be capable of detecting light from those objects. There would be a brain present which would be capable of deciphering the information sent to it. But there would be no light! The room and everything in it would look black. The appearance of black is merely a sign of the absence of light. When a room full of objects (or a table, a shirt or a sky) looks black, then the objects are not generating nor reflecting light to your eyes. And without light, there would be no sight.
The objects which we see can be placed into one of two categories: luminous objects and illuminated objects. Luminous objects are objects which generate their own light. Illuminated objects are objects which are capable of reflecting light to our eyes. The sun is an example of a luminous object, while the moon is an illuminated object. During the day, the sun generates sufficient light to illuminate objects on Earth. The blue skies, the white clouds, the green grass, the colored leaves of fall, the neighbor's house, and the car approaching the intersection are all seen as a result of light from the sun (the luminous object) reflecting off the illuminated objects and traveling to our eyes. Without the light from the luminous objects, these illuminated objects would not be seen. During the evening when the Earth has rotated to a position where the light from the sun can no longer reach our part of the Earth (due to its inability to bend around the spherical shape of the Earth), objects on Earth appear black (or at least so dark that we could say they are nearly black). In the absence of a porch light or a street light, the neighbor's house can no longer be seen; the grass is no longer green, but rather black; the leaves on the trees are dark; and were it not for the headlights of the car, it would not be seen approaching the intersection. Without luminous objects generating light which propagates through space to illuminate non-luminous objects, those non-luminous objects cannot bee seen. Without light, there would be no sight.
A common Physics demonstration involves the directing of a laser beam across the room. With the room lights off, the laser is turned on and its beam is directed towards a plane mirror. The presence of the light beam cannot be detected as it travels towards the mirror. Furthermore, the light beam cannot be detected after reflecting off the mirror and traveling through the air towards a wall in the room. The only locations where the presence of the light beam can be detected are at the location where the light beam strikes the mirror and at the location where the light beam strikes a wall. At these two locations, a portion of the light in the beam is reflecting off the objects (the mirror and the wall) and traveling towards the students' eyes. And since the detection of objects is dependent upon light traveling from that object to the eye, these are the only two locations where one can detect the light beam. But in between the laser and the mirror, the light beam cannot be detected. There is nothing present in the region between the laser and the mirror which is capable of reflecting the light of the beam to students' eyes.
Light, form of energy visible to the human eye that is radiated by moving charged particles. Light from the Sun provides the energy needed for plant growth. Plants convert the energy in sunlight into storable chemical form through a process called photosynthesis. Petroleum, coal, and natural gas are the remains of plants that lived millions of years ago, and the energy these fuels release when they burn is the chemical energy converted from sunlight. When animals digest the plants and animals they eat, they also release energy stored by photosynthesis.
Scientists have learned through experimentation that light behaves like a particle at times and like a wave at other times. The particle-like features are called photons. Photons are different from particles of matter in that they have no mass and always move at the constant speed of about 300,000 km/sec (186,000 mi/sec) when they are in a vacuum. When light diffracts, or bends slightly as it passes around a corner, it shows wavelike behavior. The waves associated with light are called electromagnetic waves because they consist of changing electric and magneticfields. Sources of light differ in how they provide energy to the charged particles, such as electrons, whose motion creates the light. If the energy comes from heat, then the source is called incandescent. If the energy comes from another source, such as chemical or electric energy, the source is called luminescent.
The waves that accompany light are made up of oscillating, or vibrating, electric and magnetic fields, which are force fields that surround charged particles and influence other charged particles in their vicinity. These electric and magnetic fields change strength and direction at right angles, or perpendicularly, to each other in a plane (vertically and horizontally for instance). The electromagnetic wave formed by these fields travels in a direction perpendicular to the field’s strength (coming out of the plane). The relationship between the fields and the wave formed can be understood by imagining a wave in a taut rope. Grasping the rope and moving it up and down simulates the action of a moving charge upon the electric field. It creates a wave that travels along the rope in a direction that is perpendicular to the initial up and down movement.
Because electromagnetic waves are transverse—that is, the vibration that creates them is perpendicular to the direction in which they travel, they are similar to waves on a rope or waves traveling on the surface of water. Unlike these waves, however, which require a rope or water, light does not need a medium, or substance, through which to travel. Light from the Sun and distant stars reaches Earth by traveling through the vacuum of space.
The waves associated with natural sources of light are irregular, like the water waves in a busy harbor. Scientists think of such waves as being made up of many smooth waves, where the motion is regular and the wave stretches out indefinitely with regularly spaced peaks and valleys. Such regular waves are called monochromatic because they correspond to a single color of light.
Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
For diurnal species (species that are active during the day), light is important for many reasons. Obviously, it is required for vision, and most birds have highly developed sight. For many species of animals, full-spectrum light is required for the conversion of cholesterol to vitamin D. Light and its changing cycles -- photoperiodicity is used by animals to synchronize their biological clocks. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals.
Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom. The extremely large eye leaves little room in the head for anything else. For example. an ostrich eye is 2 inches in diameter, an owl eye is one-third the entire head weight, and the buzzard eye has four times the visual acuity (sharpness) of a human eye.
Photoperiodicity has long been studied in birds as a means of inducing reproduction. Day length is detected by the pineal gland. The adrenal gland is located in the brain between the cerebella hemispheres and the cerebellum. It has numerous functions, one of which is photoreceptor and regulator of circadian rhythms. Some photoreceptors are located deep within the brain and are not dependent upon the eyes for photoreception. The hormones of the pineal gland (melatonin primarily) affect sleep, behavior and brain electrical activity. There is also evidence that melatonin influences reproductive hormonal cycles by affecting the pituitary gland. This has been very important in inducing poultry to lay eggs and to maximize egg production.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
Numerous breeders of exotic birds have used changing the day length in an attempt to manipulate breeding. however, few controlled studies have been conducted to assess its effects. Work at the department of avian sciences at the University of California at Davis and elsewhere demonstrated that long day lengths stimulate reproductive activity in cockatiels and blossom-headed parakeets. In general. birds must be exposed to short day lengths (10 hours of light, 14 hours of dark). before they can respond to long day lengths. The length of the photoperiod that may be stimulatory can only be determined experimentally for each species, but it may range from 13 to 17 hours. Ideally, it would increase gradually. Many birds will become unresponsive to this stimulus after prolonged! light stimulation. Work at UC Davis showed that cockatiels became resistant after two clutches. For pet birds, the sometimes prolonged or erratic photoperiods that they are exposed to in the home may affect them behaviorally. A bird exhibiting signs of sexual over stimulation or frustration (such as plucking) may respond to a shortened day length.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass.
Vitamin D can be toxic, so be careful not to over supplement. Birds housed outdoors do not need supplemental vitamin D. Special Effects Light affects the health and well being of people and animals in numerous ways. Dr. John Ott did some of the pioneering studies in the 1960s and 1970s. He conducted numerous studies on the effects of light on plants and animals. He utilized time-lapse photography to demonstrate plant growth and the effects of limiting the photo spectrum. Working with fluorescent lights, such as cool white, daylight white. and warm white bulbs that were limited in spectrum, some plants would not flower properly. By using light filters to further limit the light spectrum he could produce signs suggestive of viral disease in plants. He conducted similar studies in mice and found that deprivation of part of the light spectrum could produce loss of fur, skin disease, curling and loss of the tail, and inflammation of the heart muscle (myocarditis). It also affected the behavior of the mice, making some aggressive and agitated. In studies of children in school where curtains were closed and limited spectrum fluorescent lights were used, children were hyperactive and inattentive. This behavior was corrected when the lights were changed and the curtains were opened. He also equated malillumination with malnutrition.
A recent Wall Street Journal report showed how light is being used to enhance human well being. Prior to the invention of the electric light in 1879, buildings were designed with an emphasis on placement of windows to enhance natural lighting. As architects relied more on electric lighting, natural lighting of buildings was reduced. The need for energy efficiency has again affected how we design our indoor spaces for light. Recently, European countries have begun to require that a percentage of a building's light come from outdoors -- 37 percent in the Netherlands, for example.
According to a report by the Rocky Mountain Institute in Snowmass, Colorado, increasing daylight results in fewer days lost to absenteeism and fewer errors and defects. The report, "Greening the Building and the Bottom Line", cites improved heating and cooling in eight commercial buildings thanks to natural light. Installation of special skylights and-tall windows improved lighting and cut lighting costs by up to 75 percent. An unexpected effect was a 15-percent drop in employee absenteeism, as well as increased productivity and sales.
People living in northern cities that are overcast for long periods of time and receive little sunshine typically report depression. Birds housed continually indoors may also suffer from depression. Taking your wing-clipped bird outdoors for a bath in the sun is great for its plumage and its spirits. If you have the opportunity to see the plumage quality of birds housed outdoors that has access to rain and sunlight, you will be a believer.
Try to place your bird near a sunny window, but make sure it can move out of direct sunlight when it wants. A useful substitute may be a full-spectrum fluorescent bulb with the fixture close enough to the bird to provide the UV spectrum. Ideally, the bulb should be within a foot or two of the bird to provide benefits.
Remember that the capability of the bulb to produce UV does not last for the life of the bulb. The bulb can still be used for general lighting purposes after it is no longer producing full-spectrum light. Certainly, we must not forget the potential hazard of excessive UV exposure, such a skin cancer and eye disease.®
Why does light matter? Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene lanterns in the developing world with solar powered lights is equivalent to removing one vehicle from the roads here in the US.
Battery Groundwater Contamination The EPA notes that “The single largest source of mercury in garbage is household batteries, especially alkaline and button batteries. Mercury is a heavy metal with high toxicity. Long-term exposure can permanently damage the brain, kidneys, and fetuses. The major way people get exposed to mercury is by eating mercury-contaminated food, especially fish.” After kerosene and candles, the most prevalent source of lighting in the developing world is conventional flashlights. According to its web-site, the Energizer Corporation, manufactures six billion batteries annually. Consider the environmental and damage to humans when even a fraction of these batteries are sold in developing nations and improperly disposed of. We are committed to addressing this problem. Our products are powered by rechargeable batteries, which only need to be replaced every two to three years, and we are also working on a buy-back/exchange program.
Deforestation and Top Soil Erosion The actual rate of deforestation for lighting is difficult to quantify due to the lack of specific reporting data. Anecdotal reporting and common sense indicate that wood fires in developing countries are kept going long after the meal preparation to provide residual lighting. The loss of underbrush contributes to top soil erosion, which negatively impacts farmers. We intend to alleviate these two problems by reducing the consumption of wood for lighting purposes.
Health and Safety Cancer According to the World Bank, 1.6 million people die each year from indoor air pollution associated with the burning of wood, dung, agricultural residues, and coal. That is one person every twenty seconds. The World Bank also notes that 780 million people in the developing world, mostly women and children, are exposed to kerosene lantern fumes equivalent to two packs of cigarettes a day. More than two-thirds of lung cancer victims in the developing world are female, as women are the primary homemakers. Help us change these alarming statistics by giving them the gift of clean, solar light!
Accidental Fires Hundreds of thousands of people are injured or killed each year and their homes destroyed by accidental fires caused by the widespread use of kerosene lanterns. Help us reduce these preventable tragedies by replacing their kerosene lanterns with safe, solar light.
Malaria Mosquitoes are attracted to kerosene light, but they are not naturally attracted to light given off by white light emitting diodes (LEDs). The reason for this is that mosquitoes have receptors which detect carbon dioxide, and kerosene lanterns emit volumes of carbon dioxide whereas LEDs do not. This suggests that people using our LED powered lights may lower their risk of contracting malaria. This is an exciting idea, and we have contacted the Center for Disease Control about conducting follow-on studies once our lights become more widely distributed.
Poverty and Economic Costs A study conducted by the joint UN Development Program/World Bank Energy Sector Management Assistance Program (ESMAP) found that rural households spending as much as US$10 per month on lighting from candles, kerosene, and dry cell batteries. In some cases, this is up to thirty percent of a developing world family’s income. BoGo Light can be an engine for change. Giving needy families free lights allows them to redirect their limited resources into other areas besides lighting – education, health, etc. Imagine the profound changes this could bring about! And the best part is that light empowers them without creating dependency.
Women Empowerment and Family Security Night time is a dangerous time for many people in developing countries, especially for refugees. It is expensive to import diesel fuel for generators and kerosene for lanterns into refugee camps; therefore, lighting is regulated and often limited both in duration and areas illuminated. Without portable lights at night, refugees must either travel at their own risk or remain homebound. Even remaining homebound, women and children are too often the victims of armed attacks and crimes in the dangerous dark. The portable, reliable BoGo Light can help liberate these people by giving them freedom of movement and freedom from fear. The freedom to move safely at night will greatly improve their quality of life, and parents equipped with lights can better observe and protect their children at night.
How is the BoGo Light distributed? The donated lights are distributed to needy individuals and families by organizations that are established and working in the developing world. These organizations include Feed The Children, Samaritan's Purse, UNHCR, and Invisible Children, as well as many other international assistance groups. Our lights have also been bulk purchased by multinational corporations such as Exxon Mobil and Perenco, as part of their community assistance programs.
Why does light matter? Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene lanterns in the developing world with solar powered lights is equivalent to removing one vehicle from the roads here in the US.
Battery Groundwater Contamination The EPA notes that “The single largest source of mercury in garbage is household batteries, especially alkaline and button batteries. Mercury is a heavy metal with high toxicity. Long-term exposure can permanently damage the brain, kidneys, and fetuses. The major way people get exposed to mercury is by eating mercury-contaminated food, especially fish.” After kerosene and candles, the most prevalent source of lighting in the developing world is conventional flashlights. According to its web-site, the Energizer Corporation, manufactures six billion batteries annually. Consider the environmental and damage to humans when even a fraction of these batteries are sold in developing nations and improperly disposed of. We are committed to addressing this problem. Our products are powered by rechargeable batteries, which only need to be replaced every two to three years, and we are also working on a buy-back/exchange program.
Deforestation and Top Soil Erosion The actual rate of deforestation for lighting is difficult to quantify due to the lack of specific reporting data. Anecdotal reporting and common sense indicate that wood fires in developing countries are kept going long after the meal preparation to provide residual lighting. The loss of underbrush contributes to top soil erosion, which negatively impacts farmers. We intend to alleviate these two problems by reducing the consumption of wood for lighting purposes.
Health and Safety Cancer According to the World Bank, 1.6 million people die each year from indoor air pollution associated with the burning of wood, dung, agricultural residues, and coal. That is one person every twenty seconds. The World Bank also notes that 780 million people in the developing world, mostly women and children, are exposed to kerosene lantern fumes equivalent to two packs of cigarettes a day. More than two-thirds of lung cancer victims in the developing world are female, as women are the primary homemakers. Help us change these alarming statistics by giving them the gift of clean, solar light!
Accidental Fires Hundreds of thousands of people are injured or killed each year and their homes destroyed by accidental fires caused by the widespread use of kerosene lanterns. Help us reduce these preventable tragedies by replacing their kerosene lanterns with safe, solar light.
Malaria Mosquitoes are attracted to kerosene light, but they are not naturally attracted to light given off by white light emitting diodes (LEDs). The reason for this is that mosquitoes have receptors which detect carbon dioxide, and kerosene lanterns emit volumes of carbon dioxide whereas LEDs do not. This suggests that people using our LED powered lights may lower their risk of contracting malaria. This is an exciting idea, and we have contacted the Center for Disease Control about conducting follow-on studies once our lights become more widely distributed.
Poverty and Economic Costs A study conducted by the joint UN Development Program/World Bank Energy Sector Management Assistance Program (ESMAP) found that rural households spending as much as US$10 per month on lighting from candles, kerosene, and dry cell batteries. In some cases, this is up to thirty percent of a developing world family’s income. BoGo Light can be an engine for change. Giving needy families free lights allows them to redirect their limited resources into other areas besides lighting – education, health, etc. Imagine the profound changes this could bring about! And the best part is that light empowers them without creating dependency.
Women Empowerment and Family Security Night time is a dangerous time for many people in developing countries, especially for refugees. It is expensive to import diesel fuel for generators and kerosene for lanterns into refugee camps; therefore, lighting is regulated and often limited both in duration and areas illuminated. Without portable lights at night, refugees must either travel at their own risk or remain homebound. Even remaining homebound, women and children are too often the victims of armed attacks and crimes in the dangerous dark. The portable, reliable BoGo Light can help liberate these people by giving them freedom of movement and freedom from fear. The freedom to move safely at night will greatly improve their quality of life, and parents equipped with lights can better observe and protect their children at night.
How is the BoGo Light distributed? The donated lights are distributed to needy individuals and families by organizations that are established and working in the developing world. These organizations include Feed The Children, Samaritan's Purse, UNHCR, and Invisible Children, as well as many other international assistance groups. Our lights have also been bulk purchased by multinational corporations such as Exxon Mobil and Perenco, as part of their community assistance programs.
Light is valuable because,light is a wonderful subject for school study partly because you can teach some facet of it at every grade level.Light is a complex phenomenon that is classically explained with a simple model based on rays and wavefronts. The Molecular Expressions Microscopy Primer explores many of the aspects of visible light starting with an introduction to electromagnetic radiation.A wide variety of sources are responsible for emission of electromagnetic radiation, and are generally categorized according to the specific spectrum of wavelengths generated by the source. Relatively long radio waves are produced by electrical current flowing through huge broadcast antennas, while much shorter visible light waves are produced by the energy state fluctuations of negatively charged electrons within atoms. The shortest form of electromagnetic radiation, gamma waves, results from decay of nuclear components at the center of the atom. The visible light that humans are able to see is usually a mixture of wavelengths whose varying composition is a function of the light source. A majority of the common natural and artificial light sources emit a broad range of wavelengths that cover the entire visible light spectrum, with some extending into the ultraviolet and infrared regions as well. For simple lighting applications, such as interior room lights, flashlights, spot and automobile headlights, and a host of other consumer, business, and technical applications, the wide wavelength spectrum is acceptable and quite useful. However, in many cases it is desirable to narrow the wavelength range of light for specific applications that require a selected region of color or frequency. This task can be easily accomplished through the use of specialized filters that transmit some wavelengths and selectively absorb, reflect, refract, or diffract unwanted wavelengths. Mankind has always been dependent upon energy from the sun's light both directly - for warmth, to dry clothing, to cook, and indirectly to provide food, water, and air. Our awareness of the value of the sun's rays revolves around the manner in which we benefit from the energy, but there are far more fundamental implications from the relationship between light and energy. Whether or not mankind devises ingenius mechanisms to harness the sun's energy, our planet and the changing environment contained within is naturally driven by the energy of sunlight.
For me,light is valuable because it helps us in our daily lives. Light, or visible light, is electromagnetic radiation of a wavelength that is visible to the human eye (about 400–700 nm). In a scientific context, the word light is sometimes used to refer to the entire electromagnetic spectrum. Moreover, in optics, the term "visible light" refers to electromagnetic radiation with wavelengths of ~300 nm (near UV) through ~1400 nm (near infrared). [1] Light is composed of elementary particles called photons. During nighttime,it help us to do our works by the use of lamps that gives light to us.And light,also helped plants to have energy,in order the plants to live.Light has many uses that has a big contribution to us.So,we should give impotance to the light. ........That`s all i can say,and thank you for the question!love u mwaaaaaaaaaaaaaahhhhhhhhh.......... Benzone Ali,crazy,sexy and waffa!hehehehehehehehehe...........
For me light is valuable because we see things every day, from the moment we get up in the morning until we go to sleep at night. We look at everything around us using light. We appreciate kids' crayon drawings, fine oil paintings, swirling computer graphics, gorgeous sunsets, a blue sky, shooting stars and rainbows. We rely on mirrors to make ourselves presentable, and sparkling gemstones to show affection. But did you ever stop to think that when we see any of these things, we are not directly connected to it? We are, in fact, seeing light -- light that somehow left objects far or near and reached our eyes. Light is all our eyes can really see. A light wave consists of energy in the form of electric and magnetic fields. The fields vibrate at right angles to the direction of movement of the wave, and at right angles to each other. Because light has both electric and magnetic fields, it is also referred to as electromagnetic radiation.The light fixtures and related equipment are some of the more expensive pieces of equipment both at initial setup up as well as in their contribution to daily operating costs. In addition to being necessary for the photosynthetic organisms we keep in our aquariums, light also provides the visual element of color. From talking to aquarists and perusing the various reef-related bulletin boards, it has been my experience that lighting and color are often a very misunderstood aspect of aquarium keeping. Given that lighting and color are important in the functional and aesthetic elements of reefkeeping, I feel it is important that hobbyists have a good understanding of light and color. The purpose of this series of articles is to provide beginning and intermediate reef aquarists with a comprehensive understanding of lighting concepts and terminology, and the ability to understand and comprehend lighting related discussions and data.Light is a form of energy, and to understand light we begin with the electromagnetic spectrum which is basically a grouping of all electromagnetic radiation arranged according to the amount of energy contained in the radiation. Visible light is a part of this electromagnetic spectrum that creates the sensation of light when it falls on the human eye.
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Natural light is so important that we would fail to thrive without it. In fact, artists and those in the know spend thousands of dollars ensuring that they have natural light — and plenty of it — in their homes and workspaces. If you are tired, sluggish, depressed, and altogether unsatisfied with your home or your workspace, one of the first things to suspect is a lack of adequate lighting. Take a good look around your workspace or your living environment. Are there big windows in the rooms where you spend a large amount of time? Are there adequate numbers of windows which give natural light as well as fresh air? In the room where you sleep, is there a large window that provides natural light as well as fresh air in the morning? This is especially important, since you will have a hard time waking up in a room that is dark in the morning, and you will have a hard time getting good sleep in a room with small windows that provide poor ventilation.
Start becoming aware of the light in the rooms where you work and relax. If you are in a dingy, dark room, it will be very hard for you to be productive at work. It will also be difficult for you to feel alert and well. Similarly, it will be hard for you to relax and rest in a room with small windows.
Large windows that let in natural light make working or just relaxing far more enjoyable. Large windows let you look out at the beauty of nature and allow you to watch the world go by. Far from being distracting, they can allow you to have the lighting you need in order to do your work without ruining your eyes. Natural lighting can be one of the best light sources to work by. Large windows that let in lots of light will also allow you to achieve a better communication between exterior world and interior world. You feel more connected with your overall environment less isolated if you have adequate windows. Of course, natural light will also ensure that you get adequate of vitamin D, which is very important to your overall health. When you spend a lot of time in dark rooms, you look pasty and you don’t feel at your best. If you are busy and do not always get to spend plenty of time outdoors, you especially need to ensure that your windows let in as much natural sunlight as possible.
If your windows are small, dark, or don’t let in enough light, consider getting renovations. Although it may seem extreme, the cost, time, and effort of renovations when it comes to windows is well worth it. Not only can good windows save your eyesight, but they can also ensure that you are as receptive, happy, and healthy as possible. Look online for inexpensive windows solutions, and be sure to read all about all the window options available today. From vinyl windows to old-fashioned wooden frames, you’re sure to find a natural lighting solution that suits your style and your budget. While shopping, be sure to pick out some pretty blinds and curtains that will help you enjoy your new windows and your new outlook on life.
LIGHT IS VERY VALUABLE SPECIALLY 2 HUMAN.WITHOUT LIGHT WE CANT SEE THINGS DURING NIGHT TIME.LIGHT HELPS US ENABLES 2 CAPTURE MOMENTS THROUGH PHOTOGRAPH.BY DA HELP OF DA LIGHT WE CAN SEE THINGS BETTER.......
LIGHT IS VERY VALUABLE SPECIALLY 2 HUMAN.WITHOUT LIGHT WE CANT SEE THINGS DURING NIGHT TIME.LIGHT HELPS US ENABLES 2 CAPTURE MOMENTS THROUGH PHOTOGRAPH.BY DA HELP OF DA LIGHT WE CAN SEE THINGS BETTER.......
->answer: Light,for me, is NOT VALUABLE or shall i say it's NOT IMPORTANT.It's not just IMPORTANT , it's VERY VERY IMPORTANT... For LIGHT,together with heat, is the main source of ENERGY of our very own planet that's why we are here.If LIGHT is absent here on EARTH, i'm pretty sure that this planet of our's will be dim, gray, dead and there will be eternal darkness all over the place. LIGHT is a very important kind of ENERGY to our everyday living. Imagine, if there's no LIGHT in here, can we survive without it??? I guess we can't!! LIGHT gives LIFE! Would you agree with that?? Maybe you'll just say, "..OwZzZz??!!" or otherwise YES. LIGHT gives LIFE for it is the one, responsible or shall i say the main source of ENERGY which plants consume and then it will undergo into a so-called photosynthesis on which plants make their own food and these plants give off oxygen and we, humans, breathe in it and we also consume the plants,of course, by eating it so that we can survive, isn't it??... So in other words, LIGHT gives LIFE to the plants as well as to humans. For there will be no plants present if there's no LIGHT and in this case, we will die because of starving. So that's how LIGHT gives LIFE to us, humans. We also use LIGHT in everyday living. In our homes, we use electrical energy and this particular energy provides LIGHT for us. Primitive Men also used LIGHT inorder to survive especially during the "ICE AGE", that is using flame that produces LIGHT by converting chemical energy to LIGHT. So see?? See the uncomparable importance of LIGHT. Even though we don't really care of conserving LIGHT, because it's a fact that Sun is the main source of it and we can never control it,hehe, so why conserve??! Let's just enjoy every single second of the Sun's LIGHT for there will be a day that our Sun will explode leaving behind our planet dark and dead. By the way. let's just bear in our mind that we're so lucky of having an energy that is responsible for the existence of various forms of life-the so-called "LIGHT"-...
THAT'S ALL AND 'TILL THEN... AU REVOIR...MABUHAY=) -END-
yes,light is very valuable and ofcourse it is very useful in our life.like the sunlight it served as the food of every plants in the planet.through sunlight we were able to generate electric power.We can also get strenght through sunlight.As present,laser beams has been used by many people to finish their work accurately especially in high-tech agency,private or government owned establishment.
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene lanterns in the developing world with solar powered lights is equivalent to removing one vehicle from the roads here in the US. The EPA notes that “The single largest source of mercury in garbage is household batteries, especially alkaline and button batteries. Mercury is a heavy metal with high toxicity. Long-term exposure can permanently damage the brain, kidneys, and fetuses. The major way people get exposed to mercury is by eating mercury-contaminated food, especially fish.” After kerosene and candles, the most prevalent source of lighting in the developing world is conventional flashlights. According to its web-site, the Energizer Corporation, manufactures six billion batteries annually. Consider the environmental and damage to humans when even a fraction of these batteries are sold in developing nations and improperly disposed of. We are committed to addressing this problem. Our products are powered by rechargeable batteries, which only need to be replaced every two to three years, and we are also working on a buy-back/exchange program.
The actual rate of deforestation for lighting is difficult to quantify due to the lack of specific reporting data. Anecdotal reporting and common sense indicate that wood fires in developing countries are kept going long after the meal preparation to provide residual lighting. The loss of underbrush contributes to top soil erosion, which negatively impacts farmers. We intend to alleviate these two problems by reducing the consumption of wood for lighting purposes. According to the World Bank, 1.6 million people die each year from indoor air pollution associated with the burning of wood, dung, agricultural residues, and coal. That is one person every twenty seconds. The World Bank also notes that 780 million people in the developing world, mostly women and children, are exposed to kerosene lantern fumes equivalent to two packs of cigarettes a day. More than two-thirds of lung cancer victims in the developing world are female, as women are the primary homemakers. Help us change these alarming statistics by giving them the gift of clean, solar light!
Hundreds of thousands of people are injured or killed each year and their homes destroyed by accidental fires caused by the widespread use of kerosene lanterns. Help us reduce these preventable tragedies by replacing their kerosene lanterns with safe, solar light. Mosquitoes are attracted to kerosene light, but they are not naturally attracted to light given off by white light emitting diodes (LEDs). The reason for this is that mosquitoes have receptors which detect carbon dioxide, and kerosene lanterns emit volumes of carbon dioxide whereas LEDs do not. This suggests that people using our LED powered lights may lower their risk of contracting malaria. This is an exciting idea, and we have contacted the Center for Disease Control about conducting follow-on studies once our lights become more widely distributed.
A study conducted by the joint UN Development Program/World Bank Energy Sector Management Assistance Program (ESMAP) found that rural households spending as much as US$10 per month on lighting from candles, kerosene, and dry cell batteries. In some cases, this is up to thirty percent of a developing world family’s income. BoGo Light can be an engine for change. Giving needy families free lights allows them to redirect their limited resources into other areas besides lighting – education, health, etc. Imagine the profound changes this could bring about! And the best part is that light empowers them without creating dependency.
Night time is a dangerous time for many people in developing countries, especially for refugees. It is expensive to import diesel fuel for generators and kerosene for lanterns into refugee camps; therefore, lighting is regulated and often limited both in duration and areas illuminated. Without portable lights at night, refugees must either travel at their own risk or remain homebound. Even remaining homebound, women and children are too often the victims of armed attacks and crimes in the dangerous dark. The portable, reliable BoGo Light can help liberate these people by giving them freedom of movement and freedom from fear. The freedom to move safely at night will greatly improve their quality of life, and parents equipped with lights can better observe and protect their children at night.
The donated lights are distributed to needy individuals and families by organizations that are established and working in the developing world. These organizations include Feed The Children, Samaritan's Purse, UNHCR, and Invisible Children, as well as many other international assistance groups. Our lights have also been bulk purchased by multinational corporations such as Exxon Mobil and Perenco, as part of their community assistance programs.
Dear Mesdame, In my opinion light is very valuable,for without light we cannot live as simple as that.For light is the key for us to see,to see is for us to identify and to differentiate things from the other.To choose what are the things do we need and the things to be thrown out. Light is the major factor why we have the sense of sight which gives us the ability to defend ourselves from various organisms.Without it,the world would not be like this.No buildings so high,no machines made that brought us a progessive civilation and no homes for us to live.For we cannot see,we cannot build.The only thing we could see is total darkness,listening to complete silence,for we cannot identify whom we are communicating at.Cannot even move for we are afraid that we might step to something that would risks our life. Human beings and animals would be blind,alone,no helper for all things cannot see and cannot be seen.Light could be processed for our convenience. I would not make my comment longer for I am almost out of words..hehehe..All things depend upon the light,all things live through of the light and all things improved because of the light.Light powers life on Earth and thats for sure.Thats all...Thank you. Truly yours, Kenmore B. Espinoza
Light, or visible light, is electromagnetic radiation of a wavelength that is visible to the human eye (about 400–700 nm). In a scientific context, the word light is sometimes used to refer to the entire electromagnetic spectrum. Moreover, in optics, the term "visible light" refers to electromagnetic radiation with wavelengths of ~300 nm (near UV) through ~1400 nm (near infrared). [1] Light is composed of elementary particles called photons.
Three primary properties of light are:
Intensity; Frequency or wavelength and; Polarization. Light can exhibit properties of both waves and particles. This property is referred to as wave–particle duality. The study of light, known as optics, is an important research area in modern physics.
Light is everywhere in our world. We need it to see: it carries information from the world to our eyes and brains. Seeing colors and shapes is second nature to us, yet light is a perplexing phenomenon when we study it more closely.
Here are some things to think about:
Our brains and eyes act together to make extraordinary things happen in perception. Movies are sequences of still pictures. Magazine pictures are arrays of dots.
Light acts like particles—little light bullets—that stream from the source. This explains how shadows work.
Light also acts like waves—ripples in space—instead of bullets. This explains how rainbows work. In fact, light is both. This "wave-particle duality" is one of the most confusing—and wonderful—principles of physics. Scientists have spent lifetimes developing consistent physical, biological, chemical, and mathematical explanations for these principles. But we can start on the road to deeper understanding without all the equations by acting as scientists do: making observations, performing experiments, and testing our conjectures against what we see.
The activities in this lab are designed to give you ideas about light—and also about how you can use technology to explore light. Collectively, the activities are a sampler—rather than comprehensive demonstration—of these two topics:
Light in Color. Color is more than decoration, and perceiving color is tricky. Three activities help you see how colors interact and how we can use color as a scientific tool.
Laws of Light. Light behaves according to special rules; for example, it usually travels in a straight line and it bounces off mirrors at the same angle it hits them.
Light is everywhere in our world. We need it to see: it carries information from the world to our eyes and brains. Seeing colors and shapes is second nature to us, yet light is a perplexing phenomenon when we study it more closely.
Here are some things to think about:
Our brains and eyes act together to make extraordinary things happen in perception. Movies are sequences of still pictures. Magazine pictures are arrays of dots.
Light acts like particles—little light bullets—that stream from the source. This explains how shadows work.
Light also acts like waves—ripples in space—instead of bullets. This explains how rainbows work. In fact, light is both. This "wave-particle duality" is one of the most confusing—and wonderful—principles of physics. Scientists have spent lifetimes developing consistent physical, biological, chemical, and mathematical explanations for these principles. But we can start on the road to deeper understanding without all the equations by acting as scientists do: making observations, performing experiments, and testing our conjectures against what we see.
The activities in this lab are designed to give you ideas about light—and also about how you can use technology to explore light. Collectively, the activities are a sampler—rather than comprehensive demonstration—of these two topics:
Light in Color. Color is more than decoration, and perceiving color is tricky. Three activities help you see how colors interact and how we can use color as a scientific tool.
Laws of Light. Light behaves according to special rules; for example, it usually travels in a straight line and it bounces off mirrors at the same angle it hits them.
Light, or visible light, is electromagnetic radiation of a wavelength that is visible to the human eye (about 400–700 nm). In a scientific context, the word light is sometimes used to refer to the entire electromagnetic spectrum. Moreover, in optics, the term "visible light" refers to electromagnetic radiation with wavelengths of ~300 nm (near UV) through ~1400 nm (near infrared). [1] Light is composed of elementary particles called photons
A beam of white light (entering upwards from the right) is dispersed into its constituent colors by its passage through a prism. The fainter beam of white light exiting to the upper right has been reflected (without dispersion) off the first surface of the prism.
The speed of light in a vacuum is exactly 299,792,458 m/s (about 186,282.397 miles per second). The speed of light depends upon the medium in which it is traveling, and the speed will be lower in a transparent medium. Although commonly called the "velocity of light", technically the word velocity is a vector quantity, having both magnitude and direction. Speed refers only to the magnitude of the velocity vector. This fixed definition of the speed of light is a result of the modern attempt, in physics, to define the basic unit of length in terms of the speed of light, rather than defining the speed of light in terms of a length.
Different physicists have attempted to measure the speed of light throughout history. Galileo attempted to measure the speed of light in the seventeenth century. A good early experiment to measure the speed of light was conducted by Ole Rømer, a Danish physicist, in 1676. Using a telescope, Ole observed the motions of Jupiter and one of its moons, Io. Noting discrepancies in the apparent period of Io's orbit, Rømer calculated that light takes about 18 minutes to traverse the diameter of Earth's orbit. Unfortunately, this was not a value that was known at that time. If Ole had known the diameter of the Earth's orbit, he would have calculated a speed of 227,000,000 m/s.
Another, more accurate, measurement of the speed of light was performed in Europe by Hippolyte Fizeau in 1849. Fizeau directed a beam of light at a mirror several kilometers away. A rotating cog wheel was placed in the path of the light beam as it traveled from the source, to the mirror and then returned to its origin. Fizeau found that at a certain rate of rotation, the beam would pass through one gap in the wheel on the way out and the next gap on the way back. Knowing the distance to the mirror, the number of teeth on the wheel, and the rate of rotation, Fizeau was able to calculate the speed of light as 313,000,000 m/s.
Léon Foucault used an experiment which used rotating mirrors to obtain a value of 298,000,000 m/s in 1862. Albert A. Michelson conducted experiments on the speed of light from 1877 until his death in 1931. He refined Foucault's methods in 1926 using improved rotating mirrors to measure the time it took light to make a round trip from Mt. Wilson to Mt. San Antonio in California. The precise measurements yielded a speed of 299,796,000 m/s.
There are many sources of light. The most common light sources are thermal: a body at a given temperature emits a characteristic spectrum of black-body radiation. Examples include sunlight (the radiation emitted by the chromosphere of the Sun at around 6,000 K peaks in the visible region of the electromagnetic spectrum), incandescent light bulbs (which emit only around 10% of their energy as visible light and the remainder as infrared), and glowing solid particles in flames. The peak of the blackbody spectrum is in the infrared for relatively cool objects like human beings. As the temperature increases, the peak shifts to shorter wavelengths, producing first a red glow, then a white one, and finally a blue color as the peak moves out of the visible part of the spectrum and into the ultraviolet. These colors can be seen when metal is heated to "red hot" or "white hot". The blue color is most commonly seen in a gas flame or a welder's torch.
Atoms emit and absorb light at characteristic energies. This produces "emission lines" in the spectrum of each atom. Emission can be spontaneous, as in light-emitting diodes, gas discharge lamps (such as neon lamps and neon signs, mercury-vapor lamps, etc.), and flames (light from the hot gas itself—so, for example, sodium in a gas flame emits characteristic yellow light). Emission can also be stimulated, as in a laser or a microwave maser.
Acceleration of a free charged particle, such as an electron, can produce visible radiation: cyclotron radiation, synchrotron radiation, and bremsstrahlung radiation are all examples of this. Particles moving through a medium faster than the speed of light in that medium can produce visible Cherenkov radiation.
Certain chemicals produce visible radiation by chemoluminescence. In living things, this process is called bioluminescence. For example, fireflies produce light by this means, and boats moving through water can disturb plankton which produce a glowing wake.
Certain substances produce light when they are illuminated by more energetic radiation, a process known as fluorescence. This is used in fluorescent lights. Some substances emit light slowly after excitation by more energetic radiation. This is known as phosphorescence.
Phosphorescent materials can also be excited by bombarding them with subatomic particles. Cathodoluminescence is one example of this.
"Lightspeed" redirects here. For other uses, see Lightspeed (disambiguation). For other uses, see Speed of light (disambiguation).
Light traveling through a medium such as air (for example, this laser) travels slower than light through a vacuum.The speed of light in the vacuum of free space is an important physical constant usually denoted by the letter c.[1] It is the speed of all electromagnetic radiation, including visible light, in free space. It is the speed of anything having zero rest mass.[2] The SI metre is defined such that the speed of light in a vacuum is exactly 299,792,458 metres per second[3] (1,079,252,848.8 km/h or 299,792.458 km/s). The speed of light can be assigned a definite numerical value because the fundamental SI unit of length, the metre, has been defined since October 21, 1983, as the distance light travels in a vacuum in 1/299,792,458 of a second; in other words, any increase in the measurement precision of the speed of light would refine the definition of the metre, but not alter the numerical value of c. The approximate value of 3×108 m/s is commonly used in rough estimates (the error is 0.07%). In imperial units, the speed of light is about 670,616,629.4 miles per hour or 983,571,056.4 feet per second (roughly one foot per nanosecond), which is about 186,282.397 miles per second.
The speed of light when it passes through a transparent or translucent material medium, like glass or air, is less than its speed in a vacuum. The ratio of the speed of light in the vacuum to the observed phase velocity is called the refractive index of the medium. See dispersion (optics). In general relativity c remains an important constant of spacetime, however the concepts of 'distance', 'time', and therefore 'speed' are not always unambiguously defined due to the curvature of spacetime caused by gravitation. When measured locally, light in a vacuum
"Lightspeed" redirects here. For other uses, see Lightspeed (disambiguation). For other uses, see Speed of light (disambiguation).
Light traveling through a medium such as air (for example, this laser) travels slower than light through a vacuum.The speed of light in the vacuum of free space is an important physical constant usually denoted by the letter c.[1] It is the speed of all electromagnetic radiation, including visible light, in free space. It is the speed of anything having zero rest mass.[2] The SI metre is defined such that the speed of light in a vacuum is exactly 299,792,458 metres per second[3] (1,079,252,848.8 km/h or 299,792.458 km/s). The speed of light can be assigned a definite numerical value because the fundamental SI unit of length, the metre, has been defined since October 21, 1983, as the distance light travels in a vacuum in 1/299,792,458 of a second; in other words, any increase in the measurement precision of the speed of light would refine the definition of the metre, but not alter the numerical value of c. The approximate value of 3×108 m/s is commonly used in rough estimates (the error is 0.07%). In imperial units, the speed of light is about 670,616,629.4 miles per hour or 983,571,056.4 feet per second (roughly one foot per nanosecond), which is about 186,282.397 miles per second.
The speed of light when it passes through a transparent or translucent material medium, like glass or air, is less than its speed in a vacuum. The ratio of the speed of light in the vacuum to the observed phase velocity is called the refractive index of the medium. See dispersion (optics). In general relativity c remains an important constant of spacetime, however the concepts of 'distance', 'time', and therefore 'speed' are not always unambiguously defined due to the curvature of spacetime caused by gravitation. When measured locally, light in a vacuum
Why is it that a beam of light radiates outward, as Young proved? What is really going on? To understand light waves, it helps to start by discussing a more familiar kind of wave -- the one we see in the water. One key point to keep in mind about the water wave is that it is not made up of water: The wave is made up of energy traveling through the water. If a wave moves across a pool from left to right, this does not mean that the water on the left side of the pool is moving to the right side of the pool. The water has actually stayed about where it was. It is the wave that has moved. When you move your hand through a filled bathtub, you make a wave, because you are putting your energy into the water A water wave consists of water molecules that vibrate up and down at right angles to the direction of motion of the wave. This type of wave is called a transverse wave.
Light waves are a little more complicated, and they do not need a medium to travel through. They can travel through a vacuum. A light wave consists of energy in the form of electric and magnetic fields. The fields vibrate at right angles to the direction of movement of the wave, and at right angles to each other. Because light has both electric and magnetic fields, it is also referred to asLight waves come in many sizes. The sizThe wavelengths of the light we can see range from 400 to 700 billionths of a meter. But the full range of wavelengths included in the definition of electromagnetic radiation extends from one billionth of a meter, as in gamma rays, to centimeters and meters, as in radio waves. Light is one small part of the spectrum. e of a wave is measured as its wavelength, which is the distance between any two corresponding points on successive waves, usually peak-to-peak or trough-to-trough electromagnetic radiation . The energy travels through the water in the form of the wave.
Why does light matter? Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene
Why does light matter? Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene
.,quail assignment 1,. ~is light valuable?~ LIGHT IS VALUABLE Yes, light is valuable, it is the agent of illumination that stimulates the sense of sight. Light is pale in color. Light is a form of energy. Electrical energy provides us with light. Without light we can't see things especially during nighttime. Light is also a source of light as a candle or lamp used to ignite something. With light human can see the aspect or appearance of other people. Light can make us animated. Light is an electromagnetic radiation such as ultraviolet, infrared or X-rays. It is the source of brightness and illumination. Light is something that makes vision possible. It is an electromagnetic radiation visible to the human eye. The sensation aroused by stimulation of the visual sense organs is light. It is a particular aspect presented to view. With light we can be enlightened, we can be informed and instruct. The traffic light is also a light. It is used to prevent traffic in the steets. Sun is the Main Source of Energy on Earth. It supplies heat and light to warm the Earth and sustain life in it. Light is valuable, so we must take good care of it.
->answer: Light is ELECTROMAGNETIC RADIATION in the wavelength range extending from about 0.4 to about 0.7 or,perharps more properly,the visual response to electromagnetic radiation in this range.By extension,the term is frequently applied to adjacent wavelength range that the eye cannot detect:ULTRAVIOLET LIGHT,infrared light and black light.In addition to wavelength,FREQUENCY,and in hertz,and wave number,inverse unit of length,atre also use to specify and designate the character and quality of the radiation.Associated with wavelength or frequency is the visual response or COLOR.The term monochromatic is applied to the idealized situation in which the length is a beam is all of one wavelength.
Light is characterized not only by wavelength,essentially a temporal quality,but also by state and degree of polarization,a geometric or directional quality,and by intensity,essentially a physical quality.The visual response to intensity is brightness.In the human visual system,at least,there is no counterpart response to the state and degree of polarization,but ample evidence exists that certain arthropods--bees in particular--are sensitive to the state of polarization of sky light.
Of course!Yes, LIGHT is valuable! For Light We can't live without light, cause light is the main source of energy,if i'm not mistaken! LIGHT is everywhere in our world. We need it to see: it carries information from the world to our eyes and brains. Seeing colors and shapes is second nature to us, yet light is a perplexing phenomenon when we study it more closely.
In our daily lives we use light! so it's simple that Light is very valuable! for we can't survive without light!!!
Definitely, light is really valuable, especially for us humans. Light is a part of our daily life here in earth. Just imagine a world conquered by darkness. We see things every day, from the moment we get up in the morning until we go to sleep at night. We look at everything around us using light. We use it in almost all important chores we’re doing. We use light that would make our home bright and even just to know if we’re in the right house and not trespassing to other properties. Light will always be a part of our daily activities including decorations or for some beautifications. It adds so much beauty in every party, gatherings or any kind of occasions or fun. We, people could not be able to survive without light. They said that education is the key to success, but, can the students study well if there is no light that would support their home or school studies like reading books, doing different school tasks or having your assignments to be done in home. We appreciate kids' crayon drawings, fine oil paintings, swirling computer graphics, gorgeous sunsets, a blue sky, shooting stars and rainbows. We rely on mirrors to make ourselves presentable and sparkling gemstones to show affection. But did you ever stop to think that when we see any of these things, we are not directly connected to it? We are, in fact, seeing light -- light that somehow left objects far or near and reached our eyes. Light is all our eyes can really see. Without the presence of light, we’ll not be aware if we’re passing in a right path or leading to the wrong one. We’ll not be able to watch out if we’re going to step in a plane floor or in a canal hole. Without light, we’ll not learn how to do many things. Light is our guide wherever we are. Light plays a big role in the development and modernization of the world. Without light, we’ll not be able to see how beautiful a rainbow is or even just to know the color of the trees, the sea, the night sky nor what characteristics a blue color has. In the dark, you’ll see nothing, but in the presence of light, you’ll see everything. And that’s how my justifications about the value of light ends.
by the way light is an electromagnetic wavelength that is visible to the human eye. LIfe is very important to both living things and nonliving things..why?..because without the presence of light plants cant produce thier own food which is so called photosynthesis..and we humans cant live without light because light make things that sorruonds us visible to our very eyes..if light doesnt existing we humans are like blinds...and we can no longer survive....as what i have said plants cant produce food so if plants cant produce food we humankind will surely die because wer dependent to plants in terms of food..not only humankind but animals as well.aside from that light also is a good vitamin D..it also cures cancer...light is an anti cancer..that is how light very important to every species living in this earth...
by the way light is an electromagnetic wavelength that is visible to the human eye. LIfe is very important to both living things and nonliving things..why?..because without the presence of light plants cant produce thier own food which is so called photosynthesis..and we humans cant live without light because light make things that sorruonds us visible to our very eyes..if light doesnt existing we humans are like blinds...and we can no longer survive....as what i have said plants cant produce food so if plants cant produce food we humankind will surely die because wer dependent to plants in terms of food..not only humankind but animals as well.aside from that light also is a good vitamin D..it also cures cancer...light is an anti cancer..that is how light very important to every species living in this earth...
yes!Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world. Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene lanterns in the developing world with solar powered lights is equivalent to removing one vehicle from the roads here in the US.
yes!Light is essential to maintaining normal, healthy physiology. Exposure to sunrise is key to synchronizing our internal body cycles to the external world (so we sleep when it is dark and are alert during the day).
Modern industrial society began to tamper with this system, though. The loss of natural light - in dark apartments, in the workplace, on shift work, etc. - creates a state of light deprivation, making us vulnerable to depressed mood, sleep problems, fatigue, ability to concentrate, and more. Nature, too, posed a new problem when humans began to migrate north, where winter nights are long and dark.
Light levels as measured in lux vary greatly between indoor and outdoor lighting. You can see from the chart below how easy it is to become light deprived in our modern, indoor society.
The importance of full spectrum lighting was demonstrated in 1973 by John Ott, a leading pioneer in the field of lighting. He conducted an experiment in which he compared the effects of full spectrum lighting with cool-white fluorescent lighting on students in separate classrooms in Sarasota, Florida. Concealed, time-lapse cameras recorded sequences of student activity. The results were significant. In cool-white fluorescent light, some students demonstrated hyperactivity, fatigue, irritability, and attention deficits. In contrast, in another class, behavior, and as well as overall academic achievement, showed marked improvement within one month after full spectrum lighting was installed . Furthermore, several learning-disabled students with extreme hyperactivity problems miraculously calmed down, and seemed to overcome some of their learning and reading problems, while in the classrooms with full spectrum lighting.
yes!light is valuable. why?Anytime we start something new, we have the power to create a fresh version of ourselves. The sum total of what we have learned comes with us into any new situation or relationship. Just like moving into a new home, how often do we really examine the things we are bringing with us?
Do they hold good memories, or are we merely dragging them along because they have always been with us? Boxes of books and magazines we haven’t read. Clothes that fit a body that may never return. Grandmother’s dresser that your sister really wanted and you don’t even like, but coveted the prize she sought?
How much easier life would be if we let go of some of the things we lug around, to make room for the person we are choosing to grow into. There is little room for a plant to grow in a crowded pot.
A new job allows the same possibilities. Bringing what you know into a fresh light with new sources of knowledge and awareness. The opportunity to find challenges to expand your mind and your horizon. To see yourself anew in a different place.
That is one of the hopes of a move, many times. To give ourselves a place to bloom and grow toward a light that may have become hidden. Light is such an important factor in the choosing of most homes. I have noticed that dark homes seem to attract secretive souls, while most people look for an abundance of natural light. Certainly there are times in our lives when we may cling to darkness, but we can always choose to turn on the light....
definitely yes.Light is an energy producing a sensation of brightness that makes vision possible.without it,we can't see.Light from the sun makes the earth warm enough for life.It is also used by plants in order to produce food for us consumers as well as for their selves.Plants do also give-off oxygen that we breathe in air.Obviously,plants can't produce these vital things without this very significant thing called light.Simply said,life here on earth would not be possible without light. . .
obviously YES,simply because here in this world where we belong without the presence of "LIGHT" all things can be considered as USELESS.we cant accomplish our daily task(assignment,house hold chores,etc.) we human are not the only one who needs light,even plants cant even survive without the presence of light.light is one of the most important factor to consider inorder for the plant to undergo through process called photosythesis so that it will produce food that is commonly needed by humans.<<
Yes, it is valuable because light is used in our everyday life. The eyes of the human beings and animals will not function without light. Even plants need sunlight to perform their food making process called photosynthesis. Thus, without light there would be no food for everyone. Without light, darkness will prevail throughout the universe.
1.A short circuit (sometimes abbreviated to short or s/c) allows a charge to flow along a different path from the one intended. The electrical opposite of a short circuit is an open circuit, which is infinite resistance between two nodes. It is common to misuse "short circuit" to describe any electrical malfunction, regardless of the actual problem. A short circuit is an accidental low-resistance connection between two nodes of an electrical circuit that are meant to be at different voltages. This results in an excessive electric current limited only by the Thevenin equivalent resistance of the rest of the network and potentially causes circuit damage, overheating, fire or explosion. Although usually the result of a fault, there are cases where short circuits are caused intentionally, for example, for the purpose of voltage-sensing crowbar circuit protectors. 2.A FUSE short for 'fusible link', is a type of overcurrent protection device. Its essential component is a metal wire or strip that melts when too much current flows. When the metal strip melts, it opens the circuit of which it's a part, and so protects the circuit from excessive current.When the fuse element blows, the indicating pin extends to activate the micro switch or relay which in turn triggers an event. 3.How do Circuit breakers Work? The circuit breaker is a simple solution to a potentially deadly problem. See more circuit breaker pictures.The circuit breaker is an absolutely essential device in the modern world, and one of the most important safety mechanisms in your home. Whenever electrical wiring in a building has too much current flowing through it, these simple machines cut the power until somebody can fix the problem. Without circuit breakers (or the alternative, fuses), household electricity would be impractical because of the potential for fires and other mayhem resulting from simple wiring problems and equipment failures. 4.When is there an overload in a circuit? An electrical overload is a situation where the wiring to or within a machine or system is subjected to a greater electric current load than it was designed to carry, leading to excessive heating of the wires and a possibility of fire. This excessive current load can be a result of electrical insulation failure ( a short circuit) or human error. A correctly designed electrical system incorporates suitable overload protection devices to prevent damage should such a situation occur. Fuses and circuit breakers are most commonly employed for this purpose. 5.Why will too many electrical devices operating at one time often blow a fuse? This excessive current load can be a result of electrical insulation failure ( a short circuit) or human error. A correctly designed electrical system incorporates suitable overload protection devices to prevent damage should such a situation occur. Fuses and circuit breakers are most commonly employed for this purpose. 6.What are the dangers of short circuit and overload? In an electrical overload, it leads to excessive heating of the wires and a possibility of fire. In a short circuit, an accidental low-resistance connection between two nodes of an electrical circuit that are meant to be at different voltages. This results in an excessive electric current limited only by the Thevenin equivalent resistance of the rest of the network and potentially causes circuit damage, overheating, fire or explosion. Although usually the result of a fault, there are cases where short circuits are caused intentionally, for example, for the purpose of voltage-sensing crowbar circuit protectors.
..maAm.. next tym na lang 2ng big questi0n? ...hehehehehe....... by`,RAPAL
88 comments:
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
Light is part of the electromagnetic spectrum, which ranges from radio waves to gamma rays. Like sound, light is a wave. . And light is a transverse wave (like a water wave). For its value, light is used mainly for industry and homes but, light still has deeper uses in our life. Sunlight on daytime is light, without it, how can we have energy to supply our needs? As we know that SUNLIGHT POWERS ALL LIFE ON earth. Light can also be created as an anti-HIV effect of hypericin as this article say;
The requirement for light in the anti-HIV-1 activity of hypericin was investigated. The hypericin concentration-dependence and light dosage-dependence of the reaction were measured. Under conditions in which hypericin caused substantial inactivation of HIV-1, there was a strict requirement for visible light. Only when the concentration of hypericin approached the cytotoxic level was there an apparent light-independent antiviral effect. This strict light-requirement for the antiviral effect could explain some of the apparently discrepant results reported by other workers. Furthermore if hypericin is contemplated for use in humans, the importance of light must be considered.
Light can also be used as a cure. Acne, wrinkles, viruses and more can be treated with light. Researchers are exploring everything from penetrating beams of light that seem to repair heart tissue after a heart attack to "light therapy" that appears to improve Alzheimer's patients' ability to sleep through the night. Doctors are remedying the side effects of cancer treatments, severe acne and other ailments just by shining high-intensity light in varying colors on the affected area.
Exploring the whole value of light may keep you face a monitor for a whole day. That's all for the first assignment! Thank you!
*end*
Good eve ma'am! here's my assignment.
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
For diurnal species (species that are active during the day), light is important for many reasons. Obviously, it is required for vision, and most birds have highly developed sight. For many species of animals, full-spectrum light is required for the conversion of cholesterol to vitamin D. Light and its changing cycles -- photoperiodicity is used by animals to synchronize their biological clocks. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals.
Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom. The extremely large eye leaves little room in the head for anything else. For example. an ostrich eye is 2 inches in diameter, an owl eye is one-third the entire head weight, and the buzzard eye has four times the visual acuity (sharpness) of a human eye.
Photoperiodicity has long been studied in birds as a means of inducing reproduction. Day length is detected by the pineal gland. The adrenal gland is located in the brain between the cerebella hemispheres and the cerebellum. It has numerous functions, one of which is photoreceptor and regulator of circadian rhythms. Some photoreceptors are located deep within the brain and are not dependent upon the eyes for photoreception. The hormones of the pineal gland (melatonin primarily) affect sleep, behavior and brain electrical activity. There is also evidence that melatonin influences reproductive hormonal cycles by affecting the pituitary gland. This has been very important in inducing poultry to lay eggs and to maximize egg production.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
Numerous breeders of exotic birds have used changing the day length in an attempt to manipulate breeding. however, few controlled studies have been conducted to assess its effects. Work at the department of avian sciences at the University of California at Davis and elsewhere demonstrated that long day lengths stimulate reproductive activity in cockatiels and blossom-headed parakeets. In general. birds must be exposed to short day lengths (10 hours of light, 14 hours of dark). before they can respond to long day lengths. The length of the photoperiod that may be stimulatory can only be determined experimentally for each species, but it may range from 13 to 17 hours. Ideally, it would increase gradually. Many birds will become unresponsive to this stimulus after prolonged! light stimulation. Work at UC Davis showed that cockatiels became resistant after two clutches. For pet birds, the sometimes prolonged or erratic photoperiods that they are exposed to in the home may affect them behaviorally. A bird exhibiting signs of sexual over stimulation or frustration (such as plucking) may respond to a shortened day length.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass.
That's all...thank you
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
There are many sources of light. The most common light sources are thermal: a body at a given temperature emits a characteristic spectrum of black-body radiation. Examples include sunlight (the radiation emitted by the chromosphere of the Sun at around 6,000 K peaks in the visible region of the electromagnetic spectrum), incandescent light bulbs (which emit only around 10% of their energy as visible light and the remainder as infrared), and glowing solid particles in flames. The peak of the blackbody spectrum is in the infrared for relatively cool objects like human beings. As the temperature increases, the peak shifts to shorter wavelengths, producing first a red glow, then a white one, and finally a blue color as the peak moves out of the visible part of the spectrum and into the ultraviolet. These colors can be seen when metal is heated to "red hot" or "white hot". The blue color is most commonly seen in a gas flame or a welder's torch.
Atoms emit and absorb light at characteristic energies. This produces "emission lines" in the spectrum of each atom. Emission can be spontaneous, as in light-emitting diodes, gas discharge lamps (such as neon lamps and neon signs, mercury-vapor lamps, etc.), and flames (light from the hot gas itself—so, for example, sodium in a gas flame emits characteristic yellow light). Emission can also be stimulated, as in a laser or a microwave maser.
Acceleration of a free charged particle, such as an electron, can produce visible radiation: cyclotron radiation, synchrotron radiation, and bremsstrahlung radiation are all examples of this. Particles moving through a medium faster than the speed of light in that medium can produce visible Cherenkov radiation.
Certain chemicals produce visible radiation by chemoluminescence. In living things, this process is called bioluminescence. For example, fireflies produce light by this means, and boats moving through water can disturb plankton which produce a glowing wake.
Certain substances produce light when they are illuminated by more energetic radiation, a process known as fluorescence. This is used in fluorescent lights. Some substances emit light slowly after excitation by more energetic radiation. This is known as phosphorescence.
Phosphorescent materials can also be excited by bombarding them with subatomic particles. Cathodoluminescence is one example of this. This mechanism is used in cathode ray tube televisions.
I thank you! "bow"...hehe:)
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
All animals are dependent on light to some extent, but birds are particularly sensitive to it. Birds deprived of sunlight may develop a variety of problems, including poor nutrient absorption, vitamin D deficiency, feather plucking, and disruption of mating and breeding patterns.
Many bird owners place their pet's cage near a window or other light source, but that may not be enough to cure the problem, since glass can act as a filter, reflecting instead of transmitting certain portions of the spectrum.
Dr. John Ott's research into the light needs of people, plants and animals led to the invention of full-spectrum lighting, a term coined by Ott. Full-spectrum lighting recreates the light-environment birds and others have in the wild. The poultry industry has already discovered that the benefits of providing full-spectrum lighting include increased egg production, larger eggs with stronger shells, and healthier birds.
What's the difference between a WIDE Spectrum and a FULL Spectrum light?
It used to be that 'full spectrum' lighting meant lights which produced both ultraviolet B, ultraviolet A and the full visible spectrum as well infrared heat. Once incandescent manufacturers figured out that people were being told to look for 'full spectrum' lighting, they started to market their wide spectrum (producing some, but not all of the visible wavelengths and no ultraviolet wavelengths) lights with 'full spectrum' in the ads and on packaging. Thus people are buying Chromalux, NeoWhite and "Full Spectrum" incandescent lights thought, incorrectly, that they are providing UVB, UVA and full visible wavelengths to their birds. In fact, incandescents are just producing, if they are putting out bright white light, only the visible spectrum; some which produce colored light, are not necessarily even producing the full visible spectrum, being corrected to increase or reduce certain parts of that spectrum.
That's all for tonight...thanks;)
yOLight, form of energy visible to the human eye that is radiated by moving charged particles. Light from the Sun provides the energy needed for plant growth. Plants convert the energy in sunlight into storable chemical form through a process called photosynthesis. Petroleum, coal, and natural gas are the remains of plants that lived millions of years ago, and the energy these fuels release when they burn is the chemical energy converted from sunlight. When animals digest the plants and animals they eat, they also release energy stored by photosynthesis.
Light
Scientists have learned through experimentation that light behaves like a particle at times and like a wave at other times. The particle-like features are called photons. Photons are different from particles of matter in that they have no mass and always move at the constant speed of about 300,000 km/sec (186,000 mi/sec) when they are in a vacuum. When light diffracts, or bends slightly as it passes around a corner, it shows wavelike behavior. The waves associated with light are called electromagnetic waves because they consist of changing electric and magnetic fields.
II. THE NATURE OF LIGHT
Sidebars
WORLD OF SCIENCE
Scientists Create Matter Out of Light
German-born American physicist Albert Einstein’s elegant equation E=mc2 predicted that energy could be converted to matter. Using a linear accelerator and high-energy laser light, physicists have done just that. This 1997 Encarta Yearbook article describes their success.
open sidebar
To understand the nature of light and how it is normally created, it is necessary to study matter at its atomic level. Atoms are the building blocks of matter, and the motion of one of their constituents, the electron, leads to the emission of light in most sources.
A. Light Emission
Light Absorption and Emission
Light Absorption and Emission
When a photon, or packet of light energy, is absorbed by an atom, the atom gains the energy of the photon, and one of the atom’s electrons may jump to a higher energy level. The atom is then said to be excited. When an electron of an excited atom falls to a lower energy level, the atom may emit the electron’s excess energy in the form of a photon. The energy levels, or orbitals, of the atoms shown here have been greatly simplified to illustrate these absorption and emission processes. For a more accurate depiction of electron orbitals, see the Atom article.
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© Microsoft Corporation. All Rights Reserved.
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Light can be emitted, or radiated, by electrons circling the nucleus of their atom. Electrons can circle atoms only in certain patterns called orbitals, and electrons have a specific amount of energy in each orbital. The amount of energy needed for each orbital is called an energy level of the atom. Electrons that circle close to the nucleus have less energy than electrons in orbitals farther from the nucleus. If the electron is in the lowest energy level, then no radiation occurs despite the motion of the electron. If an electron in a lower energy level gains some energy, it must jump to a higher level, and the atom is said to be excited. The motion of the excited electron causes it to lose energy, and it falls back to a lower level. The energy the electron releases is equal to the difference between the higher and lower energy levels. The electron may emit this quantum of energy in the form of a photon.
Each atom has a unique set of energy levels, and the energies of the corresponding photons it can emit make up what is called the atom’s spectrum. This spectrum is like a fingerprint by which the atom can be identified. The process of identifying a substance from its spectrum is called spectroscopy. The laws that describe the orbitals and energy levels of atoms are the laws of quantum theory. They were invented in the 1920s specifically to account for the radiation of light and the sizes of atoms.
B. Electromagnetic Waves
Electromagnetic Waves
The waves that accompany light are made up of oscillating, or vibrating, electric and magnetic fields, which are force fields that surround charged particles and influence other charged particles in their vicinity. These electric and magnetic fields change strength and direction at right angles, or perpendicularly, to each other in a plane (vertically and horizontally for instance). The electromagnetic wave formed by these fields travels in a direction perpendicular to the field’s strength (coming out of the plane). The relationship between the fields and the wave formed can be understood by imagining a wave in a taut rope. Grasping the rope and moving it up and down simulates the action of a moving charge upon the electric field. It creates a wave that travels along the rope in a direction that is perpendicular to the initial up and down movement.
Because electromagnetic waves are transverse—that is, the vibration that creates them is perpendicular to the direction in which they travel, they are similar to waves on a rope or waves traveling on the surface of water. Unlike these waves, however, which require a rope or water, light does not need a medium, or substance, through which to travel. Light from the Sun and distant stars reaches Earth by traveling through the vacuum of space.
The waves associated with natural sources of light are irregular, like the water waves in a busy harbor. Scientists think of such waves as being made up of many smooth waves, where the motion is regular and the wave stretches out indefinitely with regularly spaced peaks and valleys. Such regular waves are called monochromatic because they correspond to a single color of light.
1. Wavelength, Frequency, and Amplitude
The wavelength of a monochromatic wave is the distance between two consecutive wave peaks. Wavelengths of visible light can be measured in meters or in nanometers (nm), which are one-billionth of a meter (or about 0.4 ten-millionths of an inch). Frequency corresponds to the number of wavelengths that pass by a certain point in space in a given amount of time. This value is usually measured in cycles per second, or hertz (Hz). All electromagnetic waves travel at the same speed, so in one second, more short waves will pass by a point in space than will long waves. This means that shorter waves have a higher frequency than longer waves. The relationship between wavelength, speed, and frequency is expressed by the equation: wave speed equals wavelength times frequency, or
c = lf
Where c is the speed of a light wave in m/sec (3x108 m/sec in a vacuum), l is the wavelength in meters, and f is the wave’s frequency in Hz.
The amplitude of an electromagnetic wave is the height of the wave, measured from a point midway between a peak and a trough to the peak of the wave. This height corresponds to the maximum strength of the electric and magnetic fields and to the number of photons in the light.
2. Electromagnetic Spectrum
Electromagnetic Spectrum
Electromagnetic Spectrum
The electromagnetic spectrum includes radio waves, microwaves, infrared light, visible light, ultraviolet light, x rays, and gamma rays. Visible light, which makes up only a tiny fraction of the electromagnetic spectrum, is the only electromagnetic radiation that humans can perceive with their eyes.
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© Microsoft Corporation. All Rights Reserved.
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The electromagnetic spectrum refers to the entire range of frequencies or wavelengths of electromagnetic waves (see Electromagnetic Radiation). Light traditionally refers to the range of frequencies that can be seen by humans. The frequencies of these waves are very high, about one-half to three-quarters of a million billion (5 x 1014 to 7.5 x 1014) Hz. Their wavelengths range from 400 to 700 nm. X rays have wavelengths ranging from several thousandths of a nanometer to several nanometers, and radio waves have wavelengths ranging from several meters to several thousand meters.
Waves with frequencies a little lower than the range of human vision (and with wavelengths correspondingly longer) are called infrared. Waves with frequencies a little higher and wavelengths shorter than human eyes can see are called ultraviolet. About half the energy of sunlight at Earth’s surface is visible electromagnetic waves, about 3 percent is ultraviolet, and the rest is infrared.
Each different frequency or wavelength of visible light causes our eye to see a slightly different color. The longest wavelength we can see is deep red at about 700 nm. The shortest wavelength humans can detect is deep blue or violet at about 400 nm. Most light sources do not radiate monochromatic light. What we call white light, such as light from the Sun, is a mixture of all the colors in the visible spectrum, with some represented more strongly than others. Human eyes respond best to green light at 550 nm, which is also approximately the brightest color in sunlight at Earth’s surface.
3. Polarization
Polarized Light
Polarized Light
Polarized light consists of individual photons whose electric field vectors are all aligned in the same direction. Ordinary light is unpolarized because the photons are emitted in a random manner, while laser light is polarized because the photons are emitted coherently. When light passes through a polarizing filter, the electric field interacts more strongly with molecules having certain orientations. This causes the incident beam to separate into two beams, whose electric vectors are perpendicular to each other. A horizontal filter, such as the one shown, absorbs photons whose electric vectors are vertical. The remaining photons are absorbed by a second filter turned 90° to the first. At other angles the intensity of transmitted light is proportional to the square of the cosine of the angle between the two filters. In the language of quantum mechanics, polarization is called state selection. Because photons have only two states, light passing through the filter separates into only two beams.
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Polarization refers to the direction of the electric field in an electromagnetic wave. A wave whose electric field is oscillating in the vertical direction is said to be polarized in the vertical direction. The photons of such a wave would interact with matter differently than the photons of a wave polarized in the horizontal direction. The electric field in light waves from the Sun vibrates in all directions, so direct sunlight is called unpolarized. Sunlight reflected from a surface is partially polarized parallel to the surface. Polaroid sunglasses block light that is horizontally polarized and therefore reduce glare from sunlight reflecting off horizontal surfaces.
C. Photons
Photons may be described as packets of light energy, and scientists use this concept to refer to the particle-like aspect of light. Photons are unlike conventional particles, such as specks of dust or marbles, however, in that they are not limited to a specific volume in space or time. Photons are always associated with an electromagnetic wave of a definite frequency. In 1900 the German physicist Max Planck discovered that light energy is carried by photons. He found that the energy of a photon is equal to the frequency of its electromagnetic wave multiplied by a constant called h, or Planck's constant. This constant is very small because one photon carries little energy. Using the watt-second, or joule, as the unit of energy, Planck’s constant is 6.626 x 10-34 (a decimal point followed by 33 zeros and then the number 6626) joule-seconds in exponential notation. The energy consumed by a one-watt light bulb in one second, for example, is equivalent to two and a half million trillion photons of green light. Sunlight warms one square meter at the top of Earth’s atmosphere at noon at the equator with the equivalent of about 14 100-watt light bulbs. Light waves from the Sun, therefore, produce a very large number of photons.
Microsoft ® Encarta ® 2006. © 1993-2005 Microsoft Corporation. All rights reserved.
Light, form of energy visible to the human eye that is radiated by moving charged particles. Light from the Sun provides the energy needed for plant growth. Plants convert the energy in sunlight into storable chemical form through a process called photosynthesis. Petroleum, coal, and natural gas are the remains of plants that lived millions of years ago, and the energy these fuels release when they burn is the chemical energy converted from sunlight. When animals digest the plants and animals they eat, they also release energy stored by photosynthesis.
Light
Scientists have learned through experimentation that light behaves like a particle at times and like a wave at other times. The particle-like features are called photons. Photons are different from particles of matter in that they have no mass and always move at the constant speed of about 300,000 km/sec (186,000 mi/sec) when they are in a vacuum. When light diffracts, or bends slightly as it passes around a corner, it shows wavelike behavior. The waves associated with light are called electromagnetic waves because they consist of changing electric and magnetic fields.
II. THE NATURE OF LIGHT
Sidebars
WORLD OF SCIENCE
Scientists Create Matter Out of Light
German-born American physicist Albert Einstein’s elegant equation E=mc2 predicted that energy could be converted to matter. Using a linear accelerator and high-energy laser light, physicists have done just that. This 1997 Encarta Yearbook article describes their success.
open sidebar
To understand the nature of light and how it is normally created, it is necessary to study matter at its atomic level. Atoms are the building blocks of matter, and the motion of one of their constituents, the electron, leads to the emission of light in most sources.
A. Light Emission
Light Absorption and Emission
Light Absorption and Emission
When a photon, or packet of light energy, is absorbed by an atom, the atom gains the energy of the photon, and one of the atom’s electrons may jump to a higher energy level. The atom is then said to be excited. When an electron of an excited atom falls to a lower energy level, the atom may emit the electron’s excess energy in the form of a photon. The energy levels, or orbitals, of the atoms shown here have been greatly simplified to illustrate these absorption and emission processes. For a more accurate depiction of electron orbitals, see the Atom article.
Encarta Encyclopedia
© Microsoft Corporation. All Rights Reserved.
Full Size
Light can be emitted, or radiated, by electrons circling the nucleus of their atom. Electrons can circle atoms only in certain patterns called orbitals, and electrons have a specific amount of energy in each orbital. The amount of energy needed for each orbital is called an energy level of the atom. Electrons that circle close to the nucleus have less energy than electrons in orbitals farther from the nucleus. If the electron is in the lowest energy level, then no radiation occurs despite the motion of the electron. If an electron in a lower energy level gains some energy, it must jump to a higher level, and the atom is said to be excited. The motion of the excited electron causes it to lose energy, and it falls back to a lower level. The energy the electron releases is equal to the difference between the higher and lower energy levels. The electron may emit this quantum of energy in the form of a photon.
Each atom has a unique set of energy levels, and the energies of the corresponding photons it can emit make up what is called the atom’s spectrum. This spectrum is like a fingerprint by which the atom can be identified. The process of identifying a substance from its spectrum is called spectroscopy. The laws that describe the orbitals and energy levels of atoms are the laws of quantum theory. They were invented in the 1920s specifically to account for the radiation of light and the sizes of atoms.
B. Electromagnetic Waves
Electromagnetic Waves
The waves that accompany light are made up of oscillating, or vibrating, electric and magnetic fields, which are force fields that surround charged particles and influence other charged particles in their vicinity. These electric and magnetic fields change strength and direction at right angles, or perpendicularly, to each other in a plane (vertically and horizontally for instance). The electromagnetic wave formed by these fields travels in a direction perpendicular to the field’s strength (coming out of the plane). The relationship between the fields and the wave formed can be understood by imagining a wave in a taut rope. Grasping the rope and moving it up and down simulates the action of a moving charge upon the electric field. It creates a wave that travels along the rope in a direction that is perpendicular to the initial up and down movement.
Because electromagnetic waves are transverse—that is, the vibration that creates them is perpendicular to the direction in which they travel, they are similar to waves on a rope or waves traveling on the surface of water. Unlike these waves, however, which require a rope or water, light does not need a medium, or substance, through which to travel. Light from the Sun and distant stars reaches Earth by traveling through the vacuum of space.
The waves associated with natural sources of light are irregular, like the water waves in a busy harbor. Scientists think of such waves as being made up of many smooth waves, where the motion is regular and the wave stretches out indefinitely with regularly spaced peaks and valleys. Such regular waves are called monochromatic because they correspond to a single color of light.
1. Wavelength, Frequency, and Amplitude
The wavelength of a monochromatic wave is the distance between two consecutive wave peaks. Wavelengths of visible light can be measured in meters or in nanometers (nm), which are one-billionth of a meter (or about 0.4 ten-millionths of an inch). Frequency corresponds to the number of wavelengths that pass by a certain point in space in a given amount of time. This value is usually measured in cycles per second, or hertz (Hz). All electromagnetic waves travel at the same speed, so in one second, more short waves will pass by a point in space than will long waves. This means that shorter waves have a higher frequency than longer waves. The relationship between wavelength, speed, and frequency is expressed by the equation: wave speed equals wavelength times frequency, or
c = lf
Where c is the speed of a light wave in m/sec (3x108 m/sec in a vacuum), l is the wavelength in meters, and f is the wave’s frequency in Hz.
The amplitude of an electromagnetic wave is the height of the wave, measured from a point midway between a peak and a trough to the peak of the wave. This height corresponds to the maximum strength of the electric and magnetic fields and to the number of photons in the light.
2. Electromagnetic Spectrum
Electromagnetic Spectrum
Electromagnetic Spectrum
The electromagnetic spectrum includes radio waves, microwaves, infrared light, visible light, ultraviolet light, x rays, and gamma rays. Visible light, which makes up only a tiny fraction of the electromagnetic spectrum, is the only electromagnetic radiation that humans can perceive with their eyes.
Encarta Encyclopedia
© Microsoft Corporation. All Rights Reserved.
Full Size
The electromagnetic spectrum refers to the entire range of frequencies or wavelengths of electromagnetic waves (see Electromagnetic Radiation). Light traditionally refers to the range of frequencies that can be seen by humans. The frequencies of these waves are very high, about one-half to three-quarters of a million billion (5 x 1014 to 7.5 x 1014) Hz. Their wavelengths range from 400 to 700 nm. X rays have wavelengths ranging from several thousandths of a nanometer to several nanometers, and radio waves have wavelengths ranging from several meters to several thousand meters.
Waves with frequencies a little lower than the range of human vision (and with wavelengths correspondingly longer) are called infrared. Waves with frequencies a little higher and wavelengths shorter than human eyes can see are called ultraviolet. About half the energy of sunlight at Earth’s surface is visible electromagnetic waves, about 3 percent is ultraviolet, and the rest is infrared.
Each different frequency or wavelength of visible light causes our eye to see a slightly different color. The longest wavelength we can see is deep red at about 700 nm. The shortest wavelength humans can detect is deep blue or violet at about 400 nm. Most light sources do not radiate monochromatic light. What we call white light, such as light from the Sun, is a mixture of all the colors in the visible spectrum, with some represented more strongly than others. Human eyes respond best to green light at 550 nm, which is also approximately the brightest color in sunlight at Earth’s surface.
3. Polarization
Polarized Light
Polarized Light
Polarized light consists of individual photons whose electric field vectors are all aligned in the same direction. Ordinary light is unpolarized because the photons are emitted in a random manner, while laser light is polarized because the photons are emitted coherently. When light passes through a polarizing filter, the electric field interacts more strongly with molecules having certain orientations. This causes the incident beam to separate into two beams, whose electric vectors are perpendicular to each other. A horizontal filter, such as the one shown, absorbs photons whose electric vectors are vertical. The remaining photons are absorbed by a second filter turned 90° to the first. At other angles the intensity of transmitted light is proportional to the square of the cosine of the angle between the two filters. In the language of quantum mechanics, polarization is called state selection. Because photons have only two states, light passing through the filter separates into only two beams.
Encarta Encyclopedia
© Microsoft Corporation. All Rights Reserved.
Full Size
Polarization refers to the direction of the electric field in an electromagnetic wave. A wave whose electric field is oscillating in the vertical direction is said to be polarized in the vertical direction. The photons of such a wave would interact with matter differently than the photons of a wave polarized in the horizontal direction. The electric field in light waves from the Sun vibrates in all directions, so direct sunlight is called unpolarized. Sunlight reflected from a surface is partially polarized parallel to the surface. Polaroid sunglasses block light that is horizontally polarized and therefore reduce glare from sunlight reflecting off horizontal surfaces.
C. Photons
Photons may be described as packets of light energy, and scientists use this concept to refer to the particle-like aspect of light. Photons are unlike conventional particles, such as specks of dust or marbles, however, in that they are not limited to a specific volume in space or time. Photons are always associated with an electromagnetic wave of a definite frequency. In 1900 the German physicist Max Planck discovered that light energy is carried by photons. He found that the energy of a photon is equal to the frequency of its electromagnetic wave multiplied by a constant called h, or Planck's constant. This constant is very small because one photon carries little energy. Using the watt-second, or joule, as the unit of energy, Planck’s constant is 6.626 x 10-34 (a decimal point followed by 33 zeros and then the number 6626) joule-seconds in exponential notation. The energy consumed by a one-watt light bulb in one second, for example, is equivalent to two and a half million trillion photons of green light. Sunlight warms one square meter at the top of Earth’s atmosphere at noon at the equator with the equivalent of about 14 100-watt light bulbs. Light waves from the Sun, therefore, produce a very large number of photons.
The earliest speculations about light were hindered by the lack of knowledge about how the eye works. The Greek philosophers from as early as Pythagoras, who lived during the 5th century bc, believed light issued forth from visible things, but most also thought vision, as distinct from light, proceeded outward from the eye. Plato gave a version of this theory in his dialogue Timaeus, written in the 3rd century bc, which greatly influenced later thought.
Some early ideas of the Greeks, however, were correct. The philosopher and statesman Empedocles believed that light travels with finite speed, and the philosopher and scientist Aristotle accurately explained the rainbow as a kind of reflection from raindrops. The Greek mathematician Euclid understood the law of reflection and the properties of mirrors. Early thinkers also observed and recorded the phenomenon of refraction, but they did not know its mathematical law. The mathematician and astronomer Ptolemy was the first person on record to collect experimental data on optics, but he too believed vision issued from the eye. His work was further developed by Egyptian scientist Ibn al Haythen, who worked in Iraq and Egypt and was known to Europeans as Alhazen. Through logic and experimentation, Alhazen finally discounted Plato’s theory that vision issued forth from the eye. In Europe, Alhazen was the most well known among a group of Islamic scholars who preserved and built upon the classical Greek tradition. His work influenced all later investigations on light.
A. Early Scientific Theories
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WORLD OF SCIENCE
A Dynamical Theory of the Electromagnetic Field
British physicist James Clerk Maxwell, considered one of the 19th century’s most important scientists, was the first to demonstrate that light consists of electromagnetic waves. Building upon the ideas of British scientist Michael Faraday, Maxwell developed his electromagnetic theory of light. This and other works by Maxwell helped pave the way for some of the major advances in physics in the 20th century. The following is Maxwell’s treatise “A Dynamical Theory of the Electromagnetic Field” (1864), which contains the fundamental equations that describe the electromagnetic field.
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The early modern scientists Galileo, Johannes Kepler of Germany, and René Descartes of France all made contributions to the understanding of light. Descartes discussed optics and reported the law of refraction in his famous Discours de la méthode (Discourse on Method), published in 1637. The Dutch astronomer and mathematician Willebrord Snell independently discovered the law of refraction in 1620, and the law is now named after him.
During the late 1600s, an important question emerged: Is light a swarm of particles or is it a wave in some pervasive medium through which ordinary matter freely moves? English physicist Sir Isaac Newton was a proponent of the particle theory, and Huygens developed the wave theory at about the same time. At the time it seemed that wave theories could not explain optical polarization because waves that scientists were familiar with moved parallel, not perpendicular, to the direction of wave travel. On the other hand, Newton had difficulty explaining the phenomenon of interference of light. His explanation forced a wavelike property on a particle description. Newton’s great prestige coupled with the difficulty of explaining polarization caused the scientific community to favor the particle theory, even after English physicist Thomas Young analyzed a new class of interference phenomena using the wave theory in 1803.
Sidebars
GREAT WORKS OF LITERATURE
Newton on Light and Colors
English physician, mathematician, and natural philosopher Sir Isaac Newton, one of the foremost figures in the history of Western science, produced insights into the natural world that were based on rigorously conducted experiments. Latin was the language of science at the time, but Newton also expressed himself in precise and direct English, as in this letter. Here, Newton reports on his experiments with prisms, which were begun in 1666 and led him to formulate a theory of the nature of light and color.
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The wave theory was finally accepted after French physicist Augustin Fresnel supported Young’s ideas with mathematical calculations in 1815 and predicted surprising new effects. Irish mathematician Sir William Hamilton clarified the relationship between wave and particle viewpoints by developing a theory that unified optics and mechanics. Hamilton’s theory was important in the later development of quantum mechanics.
Between the time of Newton and Fresnel, scientists developed mathematical techniques to describe wave phenomena in fluids and solids. Fresnel and his successors were able to use these advances to create a theory of transverse waves that would account for the phenomenon of optical polarization. As a result, an entire wave theory of light existed in mathematical form before British physicist James Clerk Maxwell began his work on electromagnetism. In his theory of electromagnetism, Maxwell showed that electric and magnetic fields affect each other in such a way as to permit waves to travel through space. The equations he derived to describe these electromagnetic waves matched the equations scientists already knew to describe light. Maxwell’s equations, however, were more general in that they described electromagnetic phenomena other than light and they predicted waves throughout the electromagnetic spectrum. In addition, his theory gave the correct speed of light in terms of the properties of electricity and magnetism. When German physicist Gustav Hertz later detected electromagnetic waves at lower frequencies, which the theory predicted, the basic correctness of Maxwell’s theory was confirmed.
Maxwell’s work left unsolved a problem common to all wave theories of light. A wave is a continuous phenomenon, which means that when it travels, its electromagnetic field must move at each of the infinite number of points in every small part of space. When we add heat to any system to raise its temperature, the energy is shared equally among all the parts of the system that can move. When this idea is applied to light, with an infinite number of moving parts, it appears to require an infinite amount of heat to give all the parts equal energy. But thermal radiation, the process in which heated objects emit electromagnetic waves, occurs in nature with a finite amount of heat. Something that could account for this process was missing from Maxwell’s theory. In 1900 Max Planck provided the missing concept. He proposed the existence of a light quantum, a finite packet of energy that became known as the photon.
B. Modern Theory
Planck’s theory remained mystifying until Einstein showed how it could be used to explain the photoelectric effect, in which the speed of ejected electrons was related not to the intensity of light but to its frequency. This relationship was consistent with Planck’s theory, which suggested that a photon’s energy was related to its frequency. During the next two decades scientists recast all of physics to be consistent with Planck’s theory. The result was a picture of the physical world that was different from anything ever before imagined. Its essential feature is that all matter appears in physical measurements to be made of quantum bits, which are something like particles. Unlike the particles of Newtonian physics, however, a quantum particle cannot be viewed as having a definite path of movement that can be predicted through laws of motion. Quantum physics only permits the prediction of the probability of where particles may be found. The probability is the squared amplitude of a wave field, sometimes called the wave function associated with the particle. For photons the underlying probability field is what we know as the electromagnetic field. The current world view that scientists use, called the Standard Model, divides particles into two categories: fermions (building blocks of atoms, such as electrons, protons, and neutrons), which cannot exist in the same place at the same time, and bosons, such as photons, which can (see Elementary Particles). Bosons are the quantum particles associated with the force fields that act on the fermions. Just as the electromagnetic field is a combination of electric and magnetic force fields, there is an even more general field called the electroweak field. This field combines electromagnetic forces and the weak nuclear force. The photon is one of four bosons associated with this field. The other three bosons have large masses and decay, or break apart, quickly to lighter components outside the nucleus of the atom.
Heheheh it's not easY to the Values of Light....For me light is valuable in all aspect in our life....sO thAt all foR the First onlin3 asSignment...!!!Thank you!!!
Light, form of energy visible to the human eye that is radiated by moving charged particles. Light from the Sun provides the energy needed for plant growth. Plants convert the energy in sunlight into storable chemical form through a process called photosynthesis. Petroleum, coal, and natural gas are the remains of plants that lived millions of years ago, and the energy these fuels release when they burn is the chemical energy converted from sunlight. When animals digest the plants and animals they eat, they also release energy stored by photosynthesis.
Light
Scientists have learned through experimentation that light behaves like a particle at times and like a wave at other times. The particle-like features are called photons. Photons are different from particles of matter in that they have no mass and always move at the constant speed of about 300,000 km/sec (186,000 mi/sec) when they are in a vacuum. When light diffracts, or bends slightly as it passes around a corner, it shows wavelike behavior. The waves associated with light are called electromagnetic waves because they consist of changing electric and magnetic fields.
II. THE NATURE OF LIGHT
Sidebars
WORLD OF SCIENCE
Scientists Create Matter Out of Light
German-born American physicist Albert Einstein’s elegant equation E=mc2 predicted that energy could be converted to matter. Using a linear accelerator and high-energy laser light, physicists have done just that. This 1997 Encarta Yearbook article describes their success.
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To understand the nature of light and how it is normally created, it is necessary to study matter at its atomic level. Atoms are the building blocks of matter, and the motion of one of their constituents, the electron, leads to the emission of light in most sources.
A. Light Emission
Light Absorption and Emission
Light Absorption and Emission
When a photon, or packet of light energy, is absorbed by an atom, the atom gains the energy of the photon, and one of the atom’s electrons may jump to a higher energy level. The atom is then said to be excited. When an electron of an excited atom falls to a lower energy level, the atom may emit the electron’s excess energy in the form of a photon. The energy levels, or orbitals, of the atoms shown here have been greatly simplified to illustrate these absorption and emission processes. For a more accurate depiction of electron orbitals, see the Atom article.
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Light can be emitted, or radiated, by electrons circling the nucleus of their atom. Electrons can circle atoms only in certain patterns called orbitals, and electrons have a specific amount of energy in each orbital. The amount of energy needed for each orbital is called an energy level of the atom. Electrons that circle close to the nucleus have less energy than electrons in orbitals farther from the nucleus. If the electron is in the lowest energy level, then no radiation occurs despite the motion of the electron. If an electron in a lower energy level gains some energy, it must jump to a higher level, and the atom is said to be excited. The motion of the excited electron causes it to lose energy, and it falls back to a lower level. The energy the electron releases is equal to the difference between the higher and lower energy levels. The electron may emit this quantum of energy in the form of a photon.
Each atom has a unique set of energy levels, and the energies of the corresponding photons it can emit make up what is called the atom’s spectrum. This spectrum is like a fingerprint by which the atom can be identified. The process of identifying a substance from its spectrum is called spectroscopy. The laws that describe the orbitals and energy levels of atoms are the laws of quantum theory. They were invented in the 1920s specifically to account for the radiation of light and the sizes of atoms.
B. Electromagnetic Waves
Electromagnetic Waves
The waves that accompany light are made up of oscillating, or vibrating, electric and magnetic fields, which are force fields that surround charged particles and influence other charged particles in their vicinity. These electric and magnetic fields change strength and direction at right angles, or perpendicularly, to each other in a plane (vertically and horizontally for instance). The electromagnetic wave formed by these fields travels in a direction perpendicular to the field’s strength (coming out of the plane). The relationship between the fields and the wave formed can be understood by imagining a wave in a taut rope. Grasping the rope and moving it up and down simulates the action of a moving charge upon the electric field. It creates a wave that travels along the rope in a direction that is perpendicular to the initial up and down movement.
Because electromagnetic waves are transverse—that is, the vibration that creates them is perpendicular to the direction in which they travel, they are similar to waves on a rope or waves traveling on the surface of water. Unlike these waves, however, which require a rope or water, light does not need a medium, or substance, through which to travel. Light from the Sun and distant stars reaches Earth by traveling through the vacuum of space.
The waves associated with natural sources of light are irregular, like the water waves in a busy harbor. Scientists think of such waves as being made up of many smooth waves, where the motion is regular and the wave stretches out indefinitely with regularly spaced peaks and valleys. Such regular waves are called monochromatic because they correspond to a single color of light.
1. Wavelength, Frequency, and Amplitude
The wavelength of a monochromatic wave is the distance between two consecutive wave peaks. Wavelengths of visible light can be measured in meters or in nanometers (nm), which are one-billionth of a meter (or about 0.4 ten-millionths of an inch). Frequency corresponds to the number of wavelengths that pass by a certain point in space in a given amount of time. This value is usually measured in cycles per second, or hertz (Hz). All electromagnetic waves travel at the same speed, so in one second, more short waves will pass by a point in space than will long waves. This means that shorter waves have a higher frequency than longer waves. The relationship between wavelength, speed, and frequency is expressed by the equation: wave speed equals wavelength times frequency, or
c = lf
Where c is the speed of a light wave in m/sec (3x108 m/sec in a vacuum), l is the wavelength in meters, and f is the wave’s frequency in Hz.
The amplitude of an electromagnetic wave is the height of the wave, measured from a point midway between a peak and a trough to the peak of the wave. This height corresponds to the maximum strength of the electric and magnetic fields and to the number of photons in the light.
2. Electromagnetic Spectrum
Electromagnetic Spectrum
Electromagnetic Spectrum
The electromagnetic spectrum includes radio waves, microwaves, infrared light, visible light, ultraviolet light, x rays, and gamma rays. Visible light, which makes up only a tiny fraction of the electromagnetic spectrum, is the only electromagnetic radiation that humans can perceive with their eyes.
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The electromagnetic spectrum refers to the entire range of frequencies or wavelengths of electromagnetic waves (see Electromagnetic Radiation). Light traditionally refers to the range of frequencies that can be seen by humans. The frequencies of these waves are very high, about one-half to three-quarters of a million billion (5 x 1014 to 7.5 x 1014) Hz. Their wavelengths range from 400 to 700 nm. X rays have wavelengths ranging from several thousandths of a nanometer to several nanometers, and radio waves have wavelengths ranging from several meters to several thousand meters.
Waves with frequencies a little lower than the range of human vision (and with wavelengths correspondingly longer) are called infrared. Waves with frequencies a little higher and wavelengths shorter than human eyes can see are called ultraviolet. About half the energy of sunlight at Earth’s surface is visible electromagnetic waves, about 3 percent is ultraviolet, and the rest is infrared.
Each different frequency or wavelength of visible light causes our eye to see a slightly different color. The longest wavelength we can see is deep red at about 700 nm. The shortest wavelength humans can detect is deep blue or violet at about 400 nm. Most light sources do not radiate monochromatic light. What we call white light, such as light from the Sun, is a mixture of all the colors in the visible spectrum, with some represented more strongly than others. Human eyes respond best to green light at 550 nm, which is also approximately the brightest color in sunlight at Earth’s surface.
3. Polarization
Polarized Light
Polarized Light
Polarized light consists of individual photons whose electric field vectors are all aligned in the same direction. Ordinary light is unpolarized because the photons are emitted in a random manner, while laser light is polarized because the photons are emitted coherently. When light passes through a polarizing filter, the electric field interacts more strongly with molecules having certain orientations. This causes the incident beam to separate into two beams, whose electric vectors are perpendicular to each other. A horizontal filter, such as the one shown, absorbs photons whose electric vectors are vertical. The remaining photons are absorbed by a second filter turned 90° to the first. At other angles the intensity of transmitted light is proportional to the square of the cosine of the angle between the two filters. In the language of quantum mechanics, polarization is called state selection. Because photons have only two states, light passing through the filter separates into only two beams.
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Polarization refers to the direction of the electric field in an electromagnetic wave. A wave whose electric field is oscillating in the vertical direction is said to be polarized in the vertical direction. The photons of such a wave would interact with matter differently than the photons of a wave polarized in the horizontal direction. The electric field in light waves from the Sun vibrates in all directions, so direct sunlight is called unpolarized. Sunlight reflected from a surface is partially polarized parallel to the surface. Polaroid sunglasses block light that is horizontally polarized and therefore reduce glare from sunlight reflecting off horizontal surfaces.
C. Photons
Photons may be described as packets of light energy, and scientists use this concept to refer to the particle-like aspect of light. Photons are unlike conventional particles, such as specks of dust or marbles, however, in that they are not limited to a specific volume in space or time. Photons are always associated with an electromagnetic wave of a definite frequency. In 1900 the German physicist Max Planck discovered that light energy is carried by photons. He found that the energy of a photon is equal to the frequency of its electromagnetic wave multiplied by a constant called h, or Planck's constant. This constant is very small because one photon carries little energy. Using the watt-second, or joule, as the unit of energy, Planck’s constant is 6.626 x 10-34 (a decimal point followed by 33 zeros and then the number 6626) joule-seconds in exponential notation. The energy consumed by a one-watt light bulb in one second, for example, is equivalent to two and a half million trillion photons of green light. Sunlight warms one square meter at the top of Earth’s atmosphere at noon at the equator with the equivalent of about 14 100-watt light bulbs. Light waves from the Sun, therefore, produce a very large number of photons.
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Light, form of energy visible to the human eye that is radiated by moving charged particles. Light from the Sun provides the energy needed for plant growth. Plants convert the energy in sunlight into storable chemical form through a process called photosynthesis. Petroleum, coal, and natural gas are the remains of plants that lived millions of years ago, and the energy these fuels release when they burn is the chemical energy converted from sunlight. When animals digest the plants and animals they eat, they also release energy stored by photosynthesis.
Light
Scientists have learned through experimentation that light behaves like a particle at times and like a wave at other times. The particle-like features are called photons. Photons are different from particles of matter in that they have no mass and always move at the constant speed of about 300,000 km/sec (186,000 mi/sec) when they are in a vacuum. When light diffracts, or bends slightly as it passes around a corner, it shows wavelike behavior. The waves associated with light are called electromagnetic waves because they consist of changing electric and magnetic fields.
II. THE NATURE OF LIGHT
Sidebars
WORLD OF SCIENCE
Scientists Create Matter Out of Light
German-born American physicist Albert Einstein’s elegant equation E=mc2 predicted that energy could be converted to matter. Using a linear accelerator and high-energy laser light, physicists have done just that. This 1997 Encarta Yearbook article describes their success.
open sidebar
To understand the nature of light and how it is normally created, it is necessary to study matter at its atomic level. Atoms are the building blocks of matter, and the motion of one of their constituents, the electron, leads to the emission of light in most sources.
A. Light Emission
Light Absorption and Emission
Light Absorption and Emission
When a photon, or packet of light energy, is absorbed by an atom, the atom gains the energy of the photon, and one of the atom’s electrons may jump to a higher energy level. The atom is then said to be excited. When an electron of an excited atom falls to a lower energy level, the atom may emit the electron’s excess energy in the form of a photon. The energy levels, or orbitals, of the atoms shown here have been greatly simplified to illustrate these absorption and emission processes. For a more accurate depiction of electron orbitals, see the Atom article.
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Light can be emitted, or radiated, by electrons circling the nucleus of their atom. Electrons can circle atoms only in certain patterns called orbitals, and electrons have a specific amount of energy in each orbital. The amount of energy needed for each orbital is called an energy level of the atom. Electrons that circle close to the nucleus have less energy than electrons in orbitals farther from the nucleus. If the electron is in the lowest energy level, then no radiation occurs despite the motion of the electron. If an electron in a lower energy level gains some energy, it must jump to a higher level, and the atom is said to be excited. The motion of the excited electron causes it to lose energy, and it falls back to a lower level. The energy the electron releases is equal to the difference between the higher and lower energy levels. The electron may emit this quantum of energy in the form of a photon.
Each atom has a unique set of energy levels, and the energies of the corresponding photons it can emit make up what is called the atom’s spectrum. This spectrum is like a fingerprint by which the atom can be identified. The process of identifying a substance from its spectrum is called spectroscopy. The laws that describe the orbitals and energy levels of atoms are the laws of quantum theory. They were invented in the 1920s specifically to account for the radiation of light and the sizes of atoms.
B. Electromagnetic Waves
Electromagnetic Waves
The waves that accompany light are made up of oscillating, or vibrating, electric and magnetic fields, which are force fields that surround charged particles and influence other charged particles in their vicinity. These electric and magnetic fields change strength and direction at right angles, or perpendicularly, to each other in a plane (vertically and horizontally for instance). The electromagnetic wave formed by these fields travels in a direction perpendicular to the field’s strength (coming out of the plane). The relationship between the fields and the wave formed can be understood by imagining a wave in a taut rope. Grasping the rope and moving it up and down simulates the action of a moving charge upon the electric field. It creates a wave that travels along the rope in a direction that is perpendicular to the initial up and down movement.
Because electromagnetic waves are transverse—that is, the vibration that creates them is perpendicular to the direction in which they travel, they are similar to waves on a rope or waves traveling on the surface of water. Unlike these waves, however, which require a rope or water, light does not need a medium, or substance, through which to travel. Light from the Sun and distant stars reaches Earth by traveling through the vacuum of space.
The waves associated with natural sources of light are irregular, like the water waves in a busy harbor. Scientists think of such waves as being made up of many smooth waves, where the motion is regular and the wave stretches out indefinitely with regularly spaced peaks and valleys. Such regular waves are called monochromatic because they correspond to a single color of light.
1. Wavelength, Frequency, and Amplitude
The wavelength of a monochromatic wave is the distance between two consecutive wave peaks. Wavelengths of visible light can be measured in meters or in nanometers (nm), which are one-billionth of a meter (or about 0.4 ten-millionths of an inch). Frequency corresponds to the number of wavelengths that pass by a certain point in space in a given amount of time. This value is usually measured in cycles per second, or hertz (Hz). All electromagnetic waves travel at the same speed, so in one second, more short waves will pass by a point in space than will long waves. This means that shorter waves have a higher frequency than longer waves. The relationship between wavelength, speed, and frequency is expressed by the equation: wave speed equals wavelength times frequency, or
c = lf
Where c is the speed of a light wave in m/sec (3x108 m/sec in a vacuum), l is the wavelength in meters, and f is the wave’s frequency in Hz.
The amplitude of an electromagnetic wave is the height of the wave, measured from a point midway between a peak and a trough to the peak of the wave. This height corresponds to the maximum strength of the electric and magnetic fields and to the number of photons in the light.
2. Electromagnetic Spectrum
Electromagnetic Spectrum
Electromagnetic Spectrum
The electromagnetic spectrum includes radio waves, microwaves, infrared light, visible light, ultraviolet light, x rays, and gamma rays. Visible light, which makes up only a tiny fraction of the electromagnetic spectrum, is the only electromagnetic radiation that humans can perceive with their eyes.
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The electromagnetic spectrum refers to the entire range of frequencies or wavelengths of electromagnetic waves (see Electromagnetic Radiation). Light traditionally refers to the range of frequencies that can be seen by humans. The frequencies of these waves are very high, about one-half to three-quarters of a million billion (5 x 1014 to 7.5 x 1014) Hz. Their wavelengths range from 400 to 700 nm. X rays have wavelengths ranging from several thousandths of a nanometer to several nanometers, and radio waves have wavelengths ranging from several meters to several thousand meters.
Waves with frequencies a little lower than the range of human vision (and with wavelengths correspondingly longer) are called infrared. Waves with frequencies a little higher and wavelengths shorter than human eyes can see are called ultraviolet. About half the energy of sunlight at Earth’s surface is visible electromagnetic waves, about 3 percent is ultraviolet, and the rest is infrared.
Each different frequency or wavelength of visible light causes our eye to see a slightly different color. The longest wavelength we can see is deep red at about 700 nm. The shortest wavelength humans can detect is deep blue or violet at about 400 nm. Most light sources do not radiate monochromatic light. What we call white light, such as light from the Sun, is a mixture of all the colors in the visible spectrum, with some represented more strongly than others. Human eyes respond best to green light at 550 nm, which is also approximately the brightest color in sunlight at Earth’s surface.
3. Polarization
Polarized Light
Polarized Light
Polarized light consists of individual photons whose electric field vectors are all aligned in the same direction. Ordinary light is unpolarized because the photons are emitted in a random manner, while laser light is polarized because the photons are emitted coherently. When light passes through a polarizing filter, the electric field interacts more strongly with molecules having certain orientations. This causes the incident beam to separate into two beams, whose electric vectors are perpendicular to each other. A horizontal filter, such as the one shown, absorbs photons whose electric vectors are vertical. The remaining photons are absorbed by a second filter turned 90° to the first. At other angles the intensity of transmitted light is proportional to the square of the cosine of the angle between the two filters. In the language of quantum mechanics, polarization is called state selection. Because photons have only two states, light passing through the filter separates into only two beams.
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Full Size
Polarization refers to the direction of the electric field in an electromagnetic wave. A wave whose electric field is oscillating in the vertical direction is said to be polarized in the vertical direction. The photons of such a wave would interact with matter differently than the photons of a wave polarized in the horizontal direction. The electric field in light waves from the Sun vibrates in all directions, so direct sunlight is called unpolarized. Sunlight reflected from a surface is partially polarized parallel to the surface. Polaroid sunglasses block light that is horizontally polarized and therefore reduce glare from sunlight reflecting off horizontal surfaces.
C. Photons
Photons may be described as packets of light energy, and scientists use this concept to refer to the particle-like aspect of light. Photons are unlike conventional particles, such as specks of dust or marbles, however, in that they are not limited to a specific volume in space or time. Photons are always associated with an electromagnetic wave of a definite frequency. In 1900 the German physicist Max Planck discovered that light energy is carried by photons. He found that the energy of a photon is equal to the frequency of its electromagnetic wave multiplied by a constant called h, or Planck's constant. This constant is very small because one photon carries little energy. Using the watt-second, or joule, as the unit of energy, Planck’s constant is 6.626 x 10-34 (a decimal point followed by 33 zeros and then the number 6626) joule-seconds in exponential notation. The energy consumed by a one-watt light bulb in one second, for example, is equivalent to two and a half million trillion photons of green light. Sunlight warms one square meter at the top of Earth’s atmosphere at noon at the equator with the equivalent of about 14 100-watt light bulbs. Light waves from the Sun, therefore, produce a very large number of photons.
The earliest speculations about light were hindered by the lack of knowledge about how the eye works. The Greek philosophers from as early as Pythagoras, who lived during the 5th century bc, believed light issued forth from visible things, but most also thought vision, as distinct from light, proceeded outward from the eye. Plato gave a version of this theory in his dialogue Timaeus, written in the 3rd century bc, which greatly influenced later thought.
Some early ideas of the Greeks, however, were correct. The philosopher and statesman Empedocles believed that light travels with finite speed, and the philosopher and scientist Aristotle accurately explained the rainbow as a kind of reflection from raindrops. The Greek mathematician Euclid understood the law of reflection and the properties of mirrors. Early thinkers also observed and recorded the phenomenon of refraction, but they did not know its mathematical law. The mathematician and astronomer Ptolemy was the first person on record to collect experimental data on optics, but he too believed vision issued from the eye. His work was further developed by Egyptian scientist Ibn al Haythen, who worked in Iraq and Egypt and was known to Europeans as Alhazen. Through logic and experimentation, Alhazen finally discounted Plato’s theory that vision issued forth from the eye. In Europe, Alhazen was the most well known among a group of Islamic scholars who preserved and built upon the classical Greek tradition. His work influenced all later investigations on light.
A. Early Scientific Theories
Sidebars
WORLD OF SCIENCE
A Dynamical Theory of the Electromagnetic Field
British physicist James Clerk Maxwell, considered one of the 19th century’s most important scientists, was the first to demonstrate that light consists of electromagnetic waves. Building upon the ideas of British scientist Michael Faraday, Maxwell developed his electromagnetic theory of light. This and other works by Maxwell helped pave the way for some of the major advances in physics in the 20th century. The following is Maxwell’s treatise “A Dynamical Theory of the Electromagnetic Field” (1864), which contains the fundamental equations that describe the electromagnetic field.
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The early modern scientists Galileo, Johannes Kepler of Germany, and René Descartes of France all made contributions to the understanding of light. Descartes discussed optics and reported the law of refraction in his famous Discours de la méthode (Discourse on Method), published in 1637. The Dutch astronomer and mathematician Willebrord Snell independently discovered the law of refraction in 1620, and the law is now named after him.
During the late 1600s, an important question emerged: Is light a swarm of particles or is it a wave in some pervasive medium through which ordinary matter freely moves? English physicist Sir Isaac Newton was a proponent of the particle theory, and Huygens developed the wave theory at about the same time. At the time it seemed that wave theories could not explain optical polarization because waves that scientists were familiar with moved parallel, not perpendicular, to the direction of wave travel. On the other hand, Newton had difficulty explaining the phenomenon of interference of light. His explanation forced a wavelike property on a particle description. Newton’s great prestige coupled with the difficulty of explaining polarization caused the scientific community to favor the particle theory, even after English physicist Thomas Young analyzed a new class of interference phenomena using the wave theory in 1803.
Sidebars
GREAT WORKS OF LITERATURE
Newton on Light and Colors
English physician, mathematician, and natural philosopher Sir Isaac Newton, one of the foremost figures in the history of Western science, produced insights into the natural world that were based on rigorously conducted experiments. Latin was the language of science at the time, but Newton also expressed himself in precise and direct English, as in this letter. Here, Newton reports on his experiments with prisms, which were begun in 1666 and led him to formulate a theory of the nature of light and color.
open sidebar
The wave theory was finally accepted after French physicist Augustin Fresnel supported Young’s ideas with mathematical calculations in 1815 and predicted surprising new effects. Irish mathematician Sir William Hamilton clarified the relationship between wave and particle viewpoints by developing a theory that unified optics and mechanics. Hamilton’s theory was important in the later development of quantum mechanics.
Between the time of Newton and Fresnel, scientists developed mathematical techniques to describe wave phenomena in fluids and solids. Fresnel and his successors were able to use these advances to create a theory of transverse waves that would account for the phenomenon of optical polarization. As a result, an entire wave theory of light existed in mathematical form before British physicist James Clerk Maxwell began his work on electromagnetism. In his theory of electromagnetism, Maxwell showed that electric and magnetic fields affect each other in such a way as to permit waves to travel through space. The equations he derived to describe these electromagnetic waves matched the equations scientists already knew to describe light. Maxwell’s equations, however, were more general in that they described electromagnetic phenomena other than light and they predicted waves throughout the electromagnetic spectrum. In addition, his theory gave the correct speed of light in terms of the properties of electricity and magnetism. When German physicist Gustav Hertz later detected electromagnetic waves at lower frequencies, which the theory predicted, the basic correctness of Maxwell’s theory was confirmed.
Maxwell’s work left unsolved a problem common to all wave theories of light. A wave is a continuous phenomenon, which means that when it travels, its electromagnetic field must move at each of the infinite number of points in every small part of space. When we add heat to any system to raise its temperature, the energy is shared equally among all the parts of the system that can move. When this idea is applied to light, with an infinite number of moving parts, it appears to require an infinite amount of heat to give all the parts equal energy. But thermal radiation, the process in which heated objects emit electromagnetic waves, occurs in nature with a finite amount of heat. Something that could account for this process was missing from Maxwell’s theory. In 1900 Max Planck provided the missing concept. He proposed the existence of a light quantum, a finite packet of energy that became known as the photon.
B. Modern Theory
Planck’s theory remained mystifying until Einstein showed how it could be used to explain the photoelectric effect, in which the speed of ejected electrons was related not to the intensity of light but to its frequency. This relationship was consistent with Planck’s theory, which suggested that a photon’s energy was related to its frequency. During the next two decades scientists recast all of physics to be consistent with Planck’s theory. The result was a picture of the physical world that was different from anything ever before imagined. Its essential feature is that all matter appears in physical measurements to be made of quantum bits, which are something like particles. Unlike the particles of Newtonian physics, however, a quantum particle cannot be viewed as having a definite path of movement that can be predicted through laws of motion. Quantum physics only permits the prediction of the probability of where particles may be found. The probability is the squared amplitude of a wave field, sometimes called the wave function associated with the particle. For photons the underlying probability field is what we know as the electromagnetic field. The current world view that scientists use, called the Standard Model, divides particles into two categories: fermions (building blocks of atoms, such as electrons, protons, and neutrons), which cannot exist in the same place at the same time, and bosons, such as photons, which can (see Elementary Particles). Bosons are the quantum particles associated with the force fields that act on the fermions. Just as the electromagnetic field is a combination of electric and magnetic force fields, there is an even more general field called the electroweak field. This field combines electromagnetic forces and the weak nuclear force. The photon is one of four bosons associated with this field. The other three bosons have large masses and decay, or break apart, quickly to lighter components outside the nucleus of the atom.
Heheheh it's not easY to the Values of Light....For me light is valuable in all aspect in our life....sO thAt all foR the First onlin3 asSignment...!!!Thank you!!!
->gud,evening,,,maam
,,,yes,the light is valuable..
Light is everywhere in our world. We need it to see it carries information from the world to our eyes and brains. Seeing colors and shapes is second nature to us, yet light is a perplexing phenomenon when we study it more closely.
Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass
The correlation of light, melatonin regulation and its relevance to breast cancer has far-reaching implications for a 24-7 operation such as a hospital. Many theories have proposed that modern environmental causes such as electromagnetic fields or simple night-time light exposure increase the risk of breast cancer. This is true particularly if the night-time production of melatonin is interrupted, as melatonin has been shown to be part of the body’s natural defence against cancer. Taking such research into account, one can conclude that melatonin production will not be impaired when a room is in complete darkness or lit with the appropriate wavelength
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
Light is valuable.
It is a form of energy. In fact, it can be converted into other forms. In plants, light is converted into chemical energy through the process of photosynthesis which occurs in leaves. Photographic film records images by converting light into chemical energy.
Other forms of energy can be converted into light. In most of our homes, electrical enerfy provides is with light. A candle flame produces light by converting chemical energy into light.
The Sun is the main source of energy on Earth. It supplies heat and light to warm the Earth and sustain life in it. Without light, there will be eternal darkness all over Earth.
Objects such as the Sun emit light. Others, such as an electric bulb, flashlight, burning candle and fire also emit light. These are called luminous bodies. Their light reaches our eyes and we see them.
Most objects around us are nonluminous. These do not emit light but illuminated by light from other sources. These interact with the light that hits them. Those which allow light to pass through are called transparent materials; while those which do not allow the passage of light are opaque. Light bounces off or reflects from opaque materials. All objects absorb energy from the light that hits them.
In terms of color, the energy of light that is absorbed is converted to heat, which warms the colored or black object. Objects such as flowers, leaves, paint, and dyes contain pigments that absorb certain colors and reflect others.
That's all...thank you!=)
->mAgz♥
Light is simply a name for a range of electromagnetic radiation that can be detected by the human eye.
Electromagnetic radiation has a dual nature as both particles and waves. One way to look at it is as changing electric and magnetic fields which propagate through space, forming an electromagnetic wave. This wave has amplitude, which is the brightness of the light, wavelength, which is the color of the light, and an angle at which it is vibrating, called polarization.
Personal approach to Symbolic reality
Dr. Dvoretskaya Ekaterina, Russia.
Symbols exist in and throw persons. Symbols are the intermediary between the world internal and the world external, between inner and external reality of human being as a person. As Florensky wrote, symbols are the organs of our contact with reality. Symbols are openings that have pierced through in our subjectivity. Symbol is an integral and indivisible quality and the person can bear within him/herself this quality. The unique and unrepeatable person can contain within him/her the universal, as positive quality and attainment. According to Florensky, “Being has an inner aspect, which it turns towards itself, in its non-confusion with everything that is not itself; and an outer aspect, directed toward another being. There are the two aspects: they are not affixed to each other, but are in original unity. They are one and the same being, even if oriented in different directions. One aspect serves the self-affirmation of being; the other serves its revelation, its manifestation, its showing forth, or whatever name one might give to the life that connects one being with another. In the terminology of the ancients, these two aspects of being are called essence or substance, ousia, and activity or energy, energeia” (translated by Penny Burt). When the medieval thinkers say that every being has its energy, and that only non-being has none, this ontological axiom is fully approved by common sense. It means, after all, that everything that genuinely exists has life within itself and manifests that life, - testifies to its own existence - by a manifestation of its life, and in doing so, it testifies not to others only, but to itself as well. This manifestation of life is indeed the energy of being.
Symbol is a trace of sacred being in ordinary life. As Umberto Eco mentioned in “Symbol”, “Any symbol is an enigma”. Florensky defined symbol as “Being, when it’s more than itself, – this is the basic definition of a symbol. The symbol is something that reveals, through itself, that which is not itself, that which is more than itself, – and yet something that essentially announces itself through this symbol. Let’s unfold this formal definition: a symbol is that essence which fuses or mingles its energy with the energy of a more valuable essence. The symbol thereby carries within itself this more valuable essence” (translated by Penny Burt).
It is easily to say that “this more valuable essence” is God. But in our time, when struggle for freedom passed the boundary of Nietzsche’s "the God has died ", it resulted in the declaration that values of human life are not postulated on the basis of Absolute values any more. Disintegration of instances of the supreme values, ideas, and ideals entailed the mixture, flattening of noumenonality and phenomenonality. Even more, we can see through the majority of philosophical works that Society replaces God in contemporary understanding of world reality. The only one opportunity to reveal the sacred dimension of human being is to “return of the person”, as Paul Ricoeur suggested.
The person is ontological category. Person creates cosmos out of chaos. Person is possessed of cosmic beginning. According to Berdyaev, the affirmation of the supreme value of personality is not at all concern for personal salvation, but rather the expression of the person's supreme creative calling in the life of the world. It is possible because the “personality as an existential centre, presupposes capacity to feel suffering and joy. Nothing in the object world, nation or state or society, or social institution, or church, possesses this capacity” (Berdyaev). Person speaks not only as man belonging to the natural and social order, but also to a different dimension of being, to the spiritual world. Person is a form of being, higher than anything natural or social. Society is a small part of person, is merely its social condition, and the world is merely part of person. Person is the existential centre, not society and not nature. Person realizes itself in social and cosmic life, but it can do this only because that within it, it is independent from nature and from the principle of society. According to Berdyaev, the beginning of new epoch presupposes a change in human mentality, the liberation of man’s consciousness from the power of “objectness”.
Berdyaev vindicated the inequality, disparity of persons in the creativity. According to him, the temptation of an absolute equality leads to the extermination of all qualities and values, of all upsurges and ascents, in it -- is the spirit of non-being. Being was conceived in inequality, in a heightening of qualities, in individual distinctions. In it the star from star is distinguished in glory. The tendency in contemporary society to worship quantity over quality has subordinated human life to the caprice of the human passions, the interests and strivings for well-being and pleasure. Triumphant only are the utilitarian values. Everything is made subject to the good of individual people and to a mechanical quantity of people. The inward, the spiritual core of the human person is denied. Good and evil are acknowledged as relative and are evaluated as dependant upon societal usefulness. The consciousness of obligations was replaced by endless demands and pretensions. According to this world-view and world-sense, the person sets forth his demands and pretensions, independent of his qualities and services. Irresponsible pretentiousness paralyses the awareness of obligations. It is a moral ulcer, polluting our societal life. Berdyaev alerted that the "extinguishing of all qualitative distinctions" and of all the uplifting would be a return to the primordial non-being, wherewith is a complete equality, a total confusion. The uprising of the primordial chaotic non-being occurs periodically within history, whole societal movements can be reflective of its light.
The appeal to symbolic reality allows us to overcome personal boundaries. In Bakhtin’s words, person as “organic unity” is capable of “transcending itself that is, exceeding its own boundaries”. A “transcending of self” is the activity of “creation”. This personal activity translates belief into reality. And this closely resembles what we have called “the sacrifice of self”. To be open person needs to come into time. Time’s dimension from the beginning till end gives inner tension to human being between birth and death. This time’s perspective shapes possibility of identification with question “who is coming?’ Person tries to answer “It’s me”. Person exists as embodied person. It defines spatio-temporal life of person. This spatio-temporal dimension of person discovers his/her unique existence. This uniqueness shapes by fact of the death.
The unity of living person fixes by forthcoming death. Mikhail Bulgakov wrote in “The Master and Margarita”: “Yes, man is mortal, but that would be only half the trouble. The worst of it is that he's sometimes unexpectedly mortal - there’s the trick!” This unexpectedness allows person to feel vigilance. In this case person transcends spatio-temporal boundaries of “here and now” and uncovers activity itself. When the feeling of death becomes dull, the consciousness loses the alarm clock awaking to presence as to wakefulness. Then the soul alive has already finished his/her metamorphosis in “there-life”, and format Dasein is replaced by an empty shell. This felling of death pierces the personal existence and personality as an existential centre and presupposes capacity to feel suffering and joy. The sweetness of life arises from influence of the poison of death and the fact of desire occurs. Eternity calls never can permeate into motive of desire or even a simple inclination. Such motivation belongs only to mortal beings. The Beauty principally exists in the forms of deficit and scarcity because of complicacy to time unlike eternity. Socrates asserted that possibility to estimate a person life as happy or unfortunate arises only after death of the person. The life pierced by call of death discovers valuability.
The inequality of mortal persons is shown in all level of existence: in deep feelings of life and death, in intensity of life, in admissibility of present another, in symbolically equipped reality and especially in accesses to the centers of condensation of vitality itself. For the last one there is on the first place to be bodily demanded and beloved. Even further being in postmortality could develop differently for various persons. The degree of unpredictability here does not concede lifetime unpredictability. But anyway, it could open the new chance. For example, chance of ascension to true scales of the person which are not represented in given still-real body.
According to Florensky, a spatio-temporal actuality both is and is becoming, it is identical to itself both because it is a certain spatio-temporal actuality and because it is becoming a certain spatio-temporal actuality through its relatedness to other spatio-temporal actualities, and so the law of identity is always both grounded and violated. Thus, A is A and A is becoming A through not-A, i.e. through a denial of itself. He wrote, "each time it is necessary to become convinced not only of the truthfulness of the thesis p but also to clarify whether it is not half of some antinomy P" for the purpose of avoiding heresy ("hairesis [the Greek term] means choice, tendency, a disposition to something"), i.e. "a rational one-sidedness that claims to be everything".
It is necessary to clarify this understanding of spatio-temporal being by Florensky through his understanding of being itself. He explained the meaning of his “concrete metaphysics” in his work At the Watersheds of Thought (U vodorazdelov mysli) which is not translated in English yet. According to Florensky, we could say that being in full possession of itself is always present to itself. It means that being as essence discovers itself by surpassing. In existence being reveals itself as non-concealment. But in the act of revealing being keeps itself in this non-concealment and therefore being resides safety and is intact. In this case being is essence. This distinction in all-embracing unity of being is the difference between openness and safeness. This is tact or tune. Tact of “basing” and of “based” keeps this distinction in harmony. Essence and existence are intact. Here we can distinguish the inner Logos that is dividing the totality of existence from the revealed Logos. The Between which arises from this distinction highlights itself in the answering, as the one in the other. But it’s possible if being itself is all-embracing unity or being in superlative degree. From this it follows that the distinction by itself shows itself as being in its all-embracing unity and as being in a superlative degree.
Such understanding of being discovers two dimensions of personal being: 1) vertical dimension to all-embracing unity and to a superlative degree or perfectness; 2) horizontal dimension to just existence in ordinary life. Person's supreme creative calling in the life of the world presupposes holding of the exertion between these two dimensions of personal being. It’s better to understand the connection between these two dimensions of personal being through explanation of the connection between two beings by Florensky. He wrote: “the connection between beings – their mutual relation and revelation – is itself something real. Without breaking away from the centers that it connects, neither can it be reduced to them. This connection is synergy, the co-activity of beings. It necessarily reveals, through itself, both of the beings that it connects. It is not numerically identical to either being, since it is something new in relation to each one of them; but it is each one of them, since it is that which reveals the respective beings. After all, outside of and apart from its energy – and what’s more, an energy that has been assimilated – this being will remain not-discovered, not-revealed, not-known. And yet a certain energy of being can be assimilated only by the energy of the being that is doing the assimilating. If there is no medium for assimilating the stream of energy, i.e., if there is no stream of energy in response, then this means that the being on the receiving end has not shown itself as receiving, has not shown itself as actively receptive. Then, as far as the original stream of energy is concerned, this unresponsive being is – nothing: it might just as well not exist. Then the current of energy will go right through and pass this being by, without touching it, without noticing it, and without being perceived or noticed in return” (translated by Penny Burt).
Florensky tried to make it more clearly by the theory of resonance. There we cannot separate the oscillations of the resonance from the oscillations that give rise to the resonance. Florensky pointed that the resonance is no longer the activity of one circuit or the other, but the circuits’ co-activity. He elaborated the concept of synergy reasoning from it. What’s oscillating in the resonator is not only the resonator’s energy, nor the energy of the vibrator alone, but the synergy of both. And the presence of this synergy enables the two circuits, even if spatially separated, to become one. Florensky wrote: “Thus, resonance is synergy, the carrier of the beings that generate the resonance. It is more than itself: it is resonance and at the same time the cause of the resonance – that which causes the resonance to be. And, to that extent, it is the being that we regard as more valued and more important, inasmuch as it is more correct to give first place to the being that is revealed by its energy, and second place to the energy that does the revealing, but which derives its value and existence from the being which is its source. And so we’ve just hit upon the concept of a symbol” (translated by Penny Burt).
Each individual faces chaos in his own soul until he places himself in the context of his personal history. According to Florensky, “The life task of anyone is to perceive the structure and form of his family, its task, the law of its growth, its points of balance, the correlation of its different branches and their particular tasks, and, on the background of all this, to perceive one’s own place in one’s family and one’s own task, which is not one’s individual task, which one poses to oneself, but one’s task as the member of a family, as the organ of a greater whole.” Knowledge of one’s identity, as we would call it now, becomes possible only through diachronic self-analysis: “It is necessary to find one’s own place in history, to register oneself historically, to find one’s own coordinates in history, one’s genealogical latitude and longitude.” (Florensky)
Each embodied person has this genealogical latitude and longitude because of born from mother. This inheritance is mine, but not me. This is something which I have in deepness of myself, but it is still other than me. In 20th century this Otherness of me named unconsciousness. According to Freud, unconsciousness is a cauldron of seething desires, a bottomless pit of perverse and incestuous cravings. Unconsciousness’ demands push person to act in reality. The acting is blind without knowledge, but knowledge is lifeless without bottomless unconsciousness. Especially when we try to answer the question “Who I am?’ and look into deepness of our soul. As Carl Jung mentioned, if person would like to understand him/herself, it’s by “revivalist gatherings and ecstatic sects, through love and hate, through the experience of passion in every form in his own body, he would reap richer stores of knowledge than text-books a foot thick could give him”. According to Jung, unconsciousness influences all of our experiences and behaviors, most especially the emotional ones, but we only know about it indirectly, by looking at those influences. Jung suggested that we possess collective unconsciousness. It is the reservoir of our experiences as a species, a kind of knowledge we are all born with. The contents of the collective unconscious are called archetypes. Jung also called them dominants, imagos, mythological or primordial images, and a few other names, but archetypes seem to have won out over these. An archetype is an unlearned tendency to experience things in a certain way. It acts as an "organizing principle" on the things we see or do.
Umberto Eco describes Jung’s collective unconsciousness as symbolic reality. According to him, “The contents of the collective unconsciousness are the archetypes, archaic types, universal images, representations collectives: lunar, solar, vegetal, metereological representation, more comprehensible in myths, more evident in dreams and visions. Jung is explicit in saying that these symbols are neither mere signs (he uses the Greek technical word semeia) nor allegories. They are genuine symbols precisely because they are ambiguous, full of half-glimpsed meanings and in the last resorts inexhaustible. They are paradoxical because they are contradictory… If the archetypes are indescribable and infinitely interpretable, their experience cannot be but amorphous, undetermined, and unarticulated. Symbols are empty and full of meaning at the same time”.
Symbols hold two dimensions of human being: vertical and horizontal. By means of modern baggage of knowledge we could call symbols as archived files. But we should unarchive these files to identify ourselves. It could be done only by our own energy. According to Florensky, “I myself perceive this revelation to me and within me. As we’ve said, this revelation of essence is fused and mingled with the energy of my perception, laying the foundation for the entire further process of cognition. Hence, this further process of cognition in no way exceeds the original capacity of the fusion of energies, or synergy… The organ which establishes at will the connection between cognizer and cognized is the word, – and especially the name, or some equivalent that can be used as a name: the metonym” (translated by Penny Burt). Linguistics distinguishes between various forms of languages, but if the goal of all these activities is to express a meaning. Within the parameters of this single goal, activities which seem to differ quite radically are nonetheless united by a single common term: language. Florensky suggested that “The rational organism, as an integral whole, internally cohesive in many ways, responds to the energy of cognized reality with its whole being, not simply through some one of its functions…. there is really only one language – the language of the whole organism’s active self-manifestation; and only a single species of word – articulated by the whole body” (translated by Penny Burt). He mentioned that there may be some activity which turns out to be the shortest, and therefore the easiest, route to the discharge of inner energy, but the language of the articulate word is a universal instrument – the grand piano among the instruments of the spirit – the most many-sided and the most capable of serving the most various needs.
Words help us to unarchive archived files of symbols in our unconsciousness. This process preforms all the hues and directions of spiritual movements which might arise, so that each appearance of the spirit, the newest, most unexpected, the most uniquely-individual, all finds itself in such a word, finds itself a readied vessel, a ready home for its habitation. Florensky wrote: “it is the word alone, produced by the vocal organ, that makes the cognitive process possible, the word alone that makes objective what was still subjective and had not seemed even to ourselves to be the cognized truth before the word came along. On the other hand, the word pronounced sums up our inward longing for reality and places before us the cognitive urge (Sehnsucht) as a goal that has been achieved and a value that has been secured for consciousness” (translated by Penny Burt). To underline this point Florensky introduce the term isotrope from geometry. Geometry shows that however short (or long) the distance between two points in space may be, one can always construct a path along which this distance is equal to zero. The line of this path is the so-called isotrope. By establishing an isotropic connection between the points, we can make any two points directly contiguous to each other. Thus we can compare the word-utterance to this contact between cognizer and cognized along the isotrope: although remaining spatially separate, they prove to be mutually superimposed. The word is the ontological isotrope, according to Florensky. So the word is a bridge between the I and the non-I.
Words help us as certain operative system to unarchive files of collective memory. As Florensky wrote in The Pillar and Ground of the Truth: “The whole theory of knowledge is, in the final analysis, a theory of memory. Memory is the activity of assimilation in thought (i.e., creative reconstruction from representations) of that which is revealed by mystical experience in Eternity, or, in other words, the creation in Time of symbols of Eternity… One can touch once again the once-already-experienced time-transcending mystical reality that lay at the base of a single representation that has passed and that is to lie at the basis of another representation, which is coming and which is kindred to the first in the unity of mystical content.” Person uses old symbols, but fills them up with new senses. Florensky sees the process of cognition as creating on the lower planes models and schemes, and on the higher planes — symbols. According to Florensky, the symbol is the essence that carries the energy, grafted to its own, of another essence. And this other, second essence is revealed through the energy of the first – i.e., the symbol’s – essence.
But we should remember that symbolic reality holds vertical dimension of human life. This line has two orientations: to the up and to the down. Horizontal line of our ordinary life has direction from birth to death with machine coordinates. It specifies our life. Time is formed by concrete processes as a result of consecutive changes of its qualitatively new conditions. We can call this new concrete processes as detached processes, according to computer language. If there is no qualitative change, there is no time also. Time is always qualitative unity. Time opens the process of identification. The identification of qualitative unity in a time stream is possible in the presence of productive action. For this purpose, the person should understand aims of actions, means and tools for its achievement, and estimations of these actions depending both on the individual human factor, and on a cultural context as a whole.
To explain processes of “to be” and “to become” is better trough understanding of Time in Ancient Egyptian esoteric thought. There time itself was seen as having two distinct yet vital characteristics. These were expressed with two terms: neheh and djet. Instead of the three linear divisions of past, present and future, Egyptian language divided time into two ‘aspects’ which can best be understood by our concepts of ‘change’ and ‘completion’ or ‘perfection’. The concept of neheh is perhaps the closest to the modern perception of time. This is time an activity in progress or incomplete time. It is often said of neheh-time that it ‘comes’: it is time as an incessantly pulsating stream of days, months, seasons, and years. For the Egyptians ‘change’, as neheh-time, was seen as an ‘aspect’ or “representation”, as the ‘becoming one’. The conception of djet-time is considered an ‘aspect’ or ‘representation’. However, instead of the “becoming one” djet-time stresses the ‘completed one’ or “totality” in the sense of an ultimate and unalterable state of perfection. Djet-time is that which ‘remains,’ ‘lasts,’ and “endures” and this is the time in which we distinguish the completed. Djet-time belong to processes of the beyond world and to passive conditions, and neheh-time pertains to processes of real world and activity. To concern to this I would like to remain that in Russian language there is no future time and it sets a life “in the continued in infinity present”. Thus, the attempt to set action in the future or to set activity from the present into the future collides with unsolved problem at a level of grammar. There is no unequivocal form either for the first, or for the second in language itself. Russian language does not provide simpliciter for proper activity as a change of an external world or as a change of own attitude to the world.
Taking into account foresaid, we could say that symbols contain convoluted time of the concrete activity. The length of a time interval in a symbol is derivative from certain property and quality. By means of these the identification is attained, so as the self-sufficiency of the activity which necessary for the identification of the given detached process. Human activity is impossible without emotions and feelings. In accordance with this symbols fill with the potentiality of activity expressed in emotional, strong-willed concentration. They are able to reproduce plurality through singularity. From the one side, symbols create differentiation of the world of actions and forms cognitive space of the world. Cognitive space correlates with space of actions. There are the more differentiation, the more symbols and the richer cognitive space. Symbols are powerful because of potentiality of certain activity. And just of it they are fraught with danger. The same we can say about rituals as some sacred human activity. The goal of this expression is not the energies themselves – physical, occult, etc. – as registered from the outside, but rather the meaning which they introduce into the world. From the second side, we don’t know what we are doing by unarhiving of archived files. Opened activities could destroy not only somebody who discovered it, but whole system of the world. Plurality of symbols as a designation of the differentiated actions set richness and variety of processes and activities in the world and universe. Through the process of recombination the new symbol could be established. It is connected with previous symbols, but it possesses new unique inherent characteristics which distinguish it from previous qualitatively. It is possible to set some operations to join several symbols on the basis of plurality and diversity.
Symbolic reality contains chaos and cosmos as sacred by itself. The feeling of chaos creates three states which individuals find intolerable - analytic, emotional, and moral impotence. It gives rise to set religions. There are different etymological interpretations of this term: 1) as re-reading (from Latin re (again) + legio (read); 2) treating carefully (from Latin relegere); 3) re-connection (from Latin re (again) + ligare (to connect, as in English ligament). According to Geerts, religion is "...a system of symbols which acts to establish powerful, persuasive, and long-lasting moods and motivations in men [sic] by formulating conceptions of a general order of existence and clothing these conceptions with such an aura of factuality that the moods and motivations seem uniquely realistic". They are fused into what Geertz calls the "really real," which is created by "…the imbuing of a certain complex of symbols—of the metaphysics they formulate and the style of life which they recommend—with a persuasive authority which, from an analytic point of view is the essence of religious perspective". That is, these symbol systems make the ethos intellectually reasonable by being shown to represent a way of life adapted to the worldview, and to make the worldview emotionally convincing by being presented as an image well-suited to accommodate such a way of life.
Operation systems which unarchive symbols are languages. According to Umberto Eco we could call it semiotic drift, that is, the idea that by entering language we enter an unavoidable hermeneutic circle where nothing can limit the endless game of signification. But in the act of knowing we distinguish between the content of the act and its form – between what we know and how we know it. Florensky examined both orientations of thought which are already inherent in the spirit of the languages by analyzing the Aryan and Semitic language families. He wrote: “Through their etymology, the Semites have demonstrated that what they value in cognition is primarily reality, and in names – the objects, whereas the Aryans prize the rationality of the cognized, and in names – the concepts. On the one hand, nomen – omen, the name is a token; on the other, nomen – notio, the name is a concept. This is the antithesis between √shem and √gna, philosophically crowned by the names of Spinoza and Kant. If we delved into this antithesis, we would hit upon the theoretico-cognitive and then the ontological juxtaposition of the feminine receptive principle and the masculine normative one (Kabbalah)” (translated by Penny Burt).
According to Florensky, the cognized metaphysically enters into the cognizer, while the cognizer metaphysically comes out of himself, moves towards the cognized, vests it with himself. The first act is mystical perception, intrinsically mystical, whatever you may call it; while the second is the act of naming. By the first we embrace the cognized, and by the second we manifest ourselves in the world – in laboring towards the cognized. Word is orientated bilateral, first, from speaking - outside, as the activity interfering from speaking in external world, and secondly, from an external world to speaking, inside of it, as the perception received by speaking. In other words, the word will transform a life, and by a word a life is acquired to spirit. The word is magic and a word is mystical. To consider, why words are magical, it means to understand, how and why we can influence to the world by a word. Words are constructed by phonemes, morphemes and sememes. Especially the last one is created by participation of many generations of people. Sememe stays as if dead while the word is not used, but only it gets in a stream of alive speech sememe revives and still full of internal force and value. Word is the condenser of will, the condenser of attention, the condenser of all sincere life. Genes of whole person, genes of his/her personal genealogy to which he/she belongs emanate in speaking word.
Florensky wrote: “The purpose of the name was to pick out an object from the general chaos of impressions and to unite it with other objects, which had already been coordinated. The function of the name is to connect. The name de-solders the disorder of consciousness and solders together its order. It is both real and ideal. It is the beginning [arche] of articulation, the beginning of differentiation, the beginning of harmony and structure. In short, the name is not a sound, but a word, logos, i.e., the word as reason, sound as meaning, the one and the other merged together. And if this is so, then wasn’t Goethe right to translate the Word of the Gospel [John’s Logos] as Deed – Tat?. “In the beginning was the Deed [“Im Anfang war die Tat” – Faust One],” for only the word “name” can be a deed. In the word we partake of the Universal Word, Universal Reason, the Universal Deed, in which “we live, and move, and have our being [Acts 17:28]” (translated by Penny Burt).
We should remember that symbolic reality exists in and through person. The discovering of this reality is risky and danger for person. It opens vertical dimension of personal being with their up and down. Personal being as all-embracing unity including a superlative degree or perfectness presupposes the realization of either highermost and holy degree, or lowermost and sink degree. The lofty a person could rise, the below he/she could fall. In this sense, sincerely repented sinner is dear to the Lord than not sinned righteous person.
;Quail assignment 1.,
=>Is LIGHT valuable?
Yes light is valuable.
All of the following explain why is
light valuable:
=>Light is produced by luminous objects, such as fires, electric lamps and stars like the Sun. The light that we can see is called visible light, but there is also light that we cannot see, including ultraviolet light and infrared light.
=>If you switch on an electric lamp, the light seems to come on instantly. However, the light doesn't really reach your eyes in no time at all. It just takes an extremely short time, because light travels extremely quickly. Light travels very much faster than sound, which is why you see lightning in a thunderstorm before you hear the thunder clap.
=>Light travels in straight lines. It cannot bend around corners, so we cannot see around a corner unless we use a mirror. We get shadows because light cannot bend round behind an object. When the Moon moves between the Sun and the Earth, it casts a shadow or "umbra" on the Earth. This blocks or partially blocks our view of the Sun, and it is called a solar eclipse.
=>Light cannot travel through opaque objects, such as brick walls. Opaque objects can cast dark shadows when light is shone on them. Light travels through transparent objects, such as glass windows. Paper and other translucent objects let some light through, but not all of it. This is why you can see the typing on the other side of a piece of printed paper if you hold it up to a light.
=>Light can travel through a vacuum such as space, but sound cannot. Science fiction films often show explosions in space with loud bangs. In real life, you would see the explosion but not hear it.
=>We see objects because light reflected from them enters our eyes. The light from luminous objects such as stars and lamps may enter our eyes directly. Non-luminous objects do not make their own light, but we can still see them if light from a luminous object reflects or scatters off them into our eyes.
=>The three primary colours of light are red, green and blue. If all three are mixed together, we get white light. If just two of them are mixed together, we get one of three secondary colours. The secondary colours are yellow, cyan and magenta. We can make any colour of light by mixing together a different amount of red, green or blue light.
=>Colour filters only let one colour of light through and stop the other colours. For example, a green filter stops all colours passing through except green. If a red or blue filter is then placed in front, no green light can pass through. If a colour is stopped by a filter we say that it is absorbed, and if a colour passes through a filter we say that it is transmitted.
=>Objects appear white if they can reflect all the colours of the spectrum. Objects appear black if they absorb all the colours of the spectrum.
=>Coloured objects reflect some colours and absorb others. For example, a green cloth reflects green light but absorbs the other colours of the spectrum.
=>Coloured objects have different colours in coloured light, because there are fewer colours for them to reflect. For example, in blue light:
=>a white cloth would appear blue, because there is only blue light for it to reflect; a black cloth would still appear black, because it absorbs all the light; a red cloth would appear black, because there is no red light for it to reflect.
=>Refraction happens as light enters and leaves a prism. Red light is refracted the least and violet light is refracted the most. This causes the different colours in the light to spread out to form a spectrum. Separating the colours like this is called dispersion. We say that the light has been dispersed.
=>The colours in the spectrum are red, orange, yellow, green, blue, indigo and violet. It may help to remember them using ROY G BIV or Richard Of York Gave Battle In Vain.
=>Water is denser than air, so light is refracted when it travels through the surface of the water. This is why sticks seem to be bent if they are partly underwater, and why swimming pools look shallower than they really are. Refraction lets you see objects that are normally hidden.
That's all!!! thanks....
;quail assignment 1.,
-> Is LIGHT valuable?
Light is essential to maintaining normal, healthy physiology. Exposure to sunrise is key to synchronizing our internal body cycles to the external world (so we sleep when it is dark and are alert during the day).
Modern industrial society began to tamper with this system, though. The loss of natural light - in dark apartments, in the workplace, on shift work, etc. - creates a state of light deprivation, making us vulnerable to depressed mood, sleep problems, fatigue, ability to concentrate, and more. Nature, too, posed a new problem when humans began to migrate north, where winter nights are long and dark.
Light levels as measured in lux vary greatly between indoor and outdoor lighting. You can see from the chart below how easy it is to become light deprived in our modern, indoor society.
im uber and out!
thats all 4 today..........
see yah.........
end
light is life....(thats for sure)
SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light. Earth would not have any life on it without the Sun’s energy, which reaches Earth in the form of heat and light. This energy warms our days and illuminates our world. Green plants absorb sunlight and convert it to food, which these plants then use to live and grow. In this process, the plants give off the oxygen that animals breathe. Animals eat these plants for nourishment. All plant and animal life relies on the Sun’s presence. Light is also essential for the survival of most animal species. The Sun also provides—directly or indirectly—much of the energy on Earth that people use for fuel ( Solar Energy) Devices called solar cells turn sunlight into electricity. Sunlight can heat a gas or liquid, which can then be circulated through a building to heat the building. The energy stored in fossil fuels originally came from the Sun. Ancient plants used sunlight as fuel to grow. Animals consumed these plants. The plants and animals stored the energy of sunlight in the organic material that composed them. When the ancient plants and animals died and decayed, this organic material was buried and gradually turned into the petroleum, coal, and natural gas people use today. The Sun’s energy produces the winds and the movements of water that people harness to produce electricity (see Wind Energy; Water Power). The Sun heats Earth’s oceans and land, which in turn heat the air and make it circulate in the atmosphere as wind. The Sun fuels Earth’s water cycle, evaporating water from the oceans, seas, and lakes. This water returns to the ground in the form of precipitation, flowing back to the oceans through the ground and in rivers. The energy of water’s motion in rivers can be harnessed with dams..... LIGHT as medicine.,., Niels Ryberg Finsen (1860-1904), Danish physician and Nobel Prize winner who made important discoveries regarding the use of light waves in the treatment of disease. Finsen was born in Tórshavn, the capital of the Faeroe Islands, a part of Denmark located north of the British Isles. After completing his early schooling in Denmark and in Reykjavík, Iceland, Finsen attended the University of Copenhagen in Denmark, receiving his medical degree in 1891. He then taught anatomy in the university's Department of Surgery, leaving in 1893 to devote himself full-time to studying “phototherapy,” or the therapeutic effects of light. In 1896 he established the Light Institute in Copenhagen. For his groundbreaking contributions to the new field of phototherapy, Niels Finsen received the 1903 Nobel Prize in physiology or medicine. Even as a child, Finsen had been fascinated by the effects of sunlight on living things. His research as an undergraduate included experiments in which he observed how sunlight affected the tissue of insects, tadpoles, and other animals. Later Finsen decided to turn his efforts toward the treatment of human diseases. In 1893 he began to study the use of filtered sunlight in the treatment of skin lesions caused by smallpox, a viral disease. Red light—that is, light from the red end of the spectrum—with its harmful heat rays filtered out, proved successful in promoting the healing of smallpox lesions. After publishing key papers on phototherapy in 1893 and 1894, Finsen began research into the treatment of lupus vulgaris, a disfiguring skin disease caused by bacteria. Finsen had noted the findings of previous researchers, who discovered that light could kill bacteria. Focusing an artificial light through a prism, Finsen exposed diseased tissue to high concentrations of ultraviolet light. The method proved highly effective in treating lupus vulgaris. Finsen established his Light Institute in Copenhagen, where hundreds of lupus vulgaris patients were successfully treated over the next few years. The use of ultraviolet light remained the central treatment for lupus vulgaris for decades.
~oOo~
_the end_
thats all....thank you...
yours truly,
~sHaRiLyN_bLuZa~
God bless.....
~oOo~
_the end_
Of course,light is very valuable specially to human,plants and animals.The sun is the ultimate source of energy.The sun our nearest star,is our main source of light.Although it is nearly 150 million kilometres away ,the light it makes reaches the Earth in only eight minutesand is so strong that it damages our eyes if we look straight at it At night we only use light bulbs or candles for light.Compared to the sun,the light energy made by these is tiny.they can only light up objects a few metres away.Nearly all of the light and energy reaching the Earth comes from the sun which is powered by continous thermonuclear reaction,like agigantic hydrogen bomb.The moon has no light of it's own-it shines only because it reflects the Sun's light stars,however are luminous because they produce their own light.
Green plants and other producers transform light energy into chemical energy through the process called photosynthesis.Light is also an important factor in photosynthesis because it provides energy.
When much light energy is absorbed,more chlorophyll molecules are energized,causing them to capture more energy that can be used in the chemical reaction producing glucose and starch.
In our mirrors,Mirrors are coated with a reflective material, so when a beam of light strikes the surface none of it is absorbed.The beam of light is reflected away again.The light is reflected at exactly the same angleas it struck the mirror, but in the opposite direction this can be visualized as being similar to a snooker ball striking the cushion of the table and bouncing at an angle
assignment in Physics- Justin Paolo Picpic IV-Quail
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
That's all thank you!!!
GOD bless you
and
Have a nice day!
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
For diurnal species (species that are active during the day), light is important for many reasons. Obviously, it is required for vision, and most birds have highly developed sight. For many species of animals, full-spectrum light is required for the conversion of cholesterol to vitamin D. Light and its changing cycles -- photoperiodicity is used by animals to synchronize their biological clocks. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals.
Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom. The extremely large eye leaves little room in the head for anything else. For example. an ostrich eye is 2 inches in diameter, an owl eye is one-third the entire head weight, and the buzzard eye has four times the visual acuity (sharpness) of a human eye.
Photoperiodicity has long been studied in birds as a means of inducing reproduction. Day length is detected by the pineal gland. The adrenal gland is located in the brain between the cerebella hemispheres and the cerebellum. It has numerous functions, one of which is photoreceptor and regulator of circadian rhythms. Some photoreceptors are located deep within the brain and are not dependent upon the eyes for photoreception. The hormones of the pineal gland (melatonin primarily) affect sleep, behavior and brain electrical activity. There is also evidence that melatonin influences reproductive hormonal cycles by affecting the pituitary gland. This has been very important in inducing poultry to lay eggs and to maximize egg production.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
Numerous breeders of exotic birds have used changing the day length in an attempt to manipulate breeding. however, few controlled studies have been conducted to assess its effects. Work at the department of avian sciences at the University of California at Davis and elsewhere demonstrated that long day lengths stimulate reproductive activity in cockatiels and blossom-headed parakeets. In general. birds must be exposed to short day lengths (10 hours of light, 14 hours of dark). before they can respond to long day lengths. The length of the photoperiod that may be stimulatory can only be determined experimentally for each species, but it may range from 13 to 17 hours. Ideally, it would increase gradually. Many birds will become unresponsive to this stimulus after prolonged! light stimulation. Work at UC Davis showed that cockatiels became resistant after two clutches. For pet birds, the sometimes prolonged or erratic photoperiods that they are exposed to in the home may affect them behaviorally. A bird exhibiting signs of sexual over stimulation or frustration (such as plucking) may respond to a shortened day length.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass.
That's all...thank you
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
Light is part of the electromagnetic spectrum, which ranges from radio waves to gamma rays. Like sound, light is a wave. . And light is a transverse wave (like a water wave). For its value, light is used mainly for industry and homes but, light still has deeper uses in our life. Sunlight on daytime is light, without it, how can we have energy to supply our needs? As we know that SUNLIGHT POWERS ALL LIFE ON earth. Light can also be created as an anti-HIV effect of hypericin as this article say;
The requirement for light in the anti-HIV-1 activity of hypericin was investigated. The hypericin concentration-dependence and light dosage-dependence of the reaction were measured. Under conditions in which hypericin caused substantial inactivation of HIV-1, there was a strict requirement for visible light. Only when the concentration of hypericin approached the cytotoxic level was there an apparent light-independent antiviral effect. This strict light-requirement for the antiviral effect could explain some of the apparently discrepant results reported by other workers. Furthermore if hypericin is contemplated for use in humans, the importance of light must be considered.
Light can also be used as a cure. Acne, wrinkles, viruses and more can be treated with light. Researchers are exploring everything from penetrating beams of light that seem to repair heart tissue after a heart attack to "light therapy" that appears to improve Alzheimer's patients' ability to sleep through the night. Doctors are remedying the side effects of cancer treatments, severe acne and other ailments just by shining high-intensity light in varying colors on the affected area.
Exploring the whole value of light may keep you face a monitor for a whole day. That's all for the first assignment! Thank you!
*end*
>>>>>mAAUng GaBiE sA tanAn.......espEcIaLly ni mAam...
""ligh is also electromagnetic spectrum that made up of different speeds of wavelengths and include ultraviolet and infrared rays. There are several different kinds of electromagnetic waves that move at the speed of light. Many scientists worked to discover the actual speed of light.......
""After the discovery of infrared light by Herschel, a Danish physicist named Hans Christian Oersted found an electrical current that could change the direction of a compass' needle. André-Marie Ampère also found that different electrical currents could also attract or repel one another. It was in 1865 when James Clerk Maxwell proposed the idea of electromagnetism. He showed that electricity and magnetism were closely related and if made to surge back and forth, could produce alternating electromagnetic waves, which would move at the speed of light. Maxwell then concluded that light itself must be an electromagnetic wave.
Infrared, visible light, and ultraviolet are not the only types of waves. Further down past infrared lay microwaves, radar, television waves, and radio waves. Microwaves are thought to have been released during the Big Bang, which could have started the universe. These slow waves are used in microwave ovens to heat food by changing the alignment of water molecules. Even slower are radar waves. Radar is an acronym for "Radio Detection and Ranging." Radar scanners send out short radio waves and detect the echoes from objects in their path. Further down are television waves. These waves send out sound and pictures to our TV sets. The slowest known waves of all are radio waves. Not only produced by radio stations, radiowaves are sent out by stars and galaxies.
At the ultraviolet end of the spectrum are three other types of waves, all with higher frequencies than ultraviolet. Directly in front of ultraviolet is X-rays. While X-rays can pass through the soft parts of our bodies, they can not penetrate bone. This is why they are used today to take pictures of broken bones. Gamma rays are radioactive and are released by certain atomic nuclei. With their large amounts of energy they are able to penetrate metal and concrete and kill living cells. This type of wave is released by nuclear bombs, causing multitudes of destruction. The highest-energy and most frequent waves are cosmic rays. They are made up of particles of atomic nuclei, electrons, and gamma rays. The earth's atmosphere protects from these waves which come from outer space.
Though it may not seem like it, light takes time to get from one place to another. The light we see from the stars at night was emitted from the star a very long time ago. In fact, the star might have burned out by the time its rays reach us, but we can't see it because it takes times to reach our solar system.
The first clue towards the speed of light came from outer space, from the planet Jupiter. In 1676, Danish astronomer Olaus Roemer observed the difference in peroids that Jupiter's moons had to the Earth's orbit. He realized that the light reflected off the moons had a different amount of light to travel depending on the Earth's position. Using this knowledge, he used mathematics to estimate that the speed of light was 136,646 miles per second. Unfortunately, Roemer didn't know that his calculations were too low, but his work was a large accomplishment for his time.
Armand Fizeau made the first land-based estimate in 1849. Fizeau set up an experiment where he placed a light five and a half miles away from a mirror. In front of the light, he set up a wheel with toothed edges. When the light would shine, it would pass through the gap between two teeth. The mirror would reflect the beam back and would shine through the next gap between the teeth. Fizeau could then estimate the speed of light from the speed at which the toothed wheel was moving. He measured the speed at 194,410 miles per second.
A year later in 1850, Léon Foucault made some changes to Fizeau's experiment. Instead of using a toothed wheel, Foucault replaced it with a spinning mirror. The light would shine onto the spinning mirror and be reflected towards a series of stationary mirrors. By measuring the amount of distance the light had to travel and knowing how fast the mirror was spinning, Foucault figured the speed of light to be 185,093 miles per second. Foucault's results were very close to the actual speed of light.
Once lasers were invented, scientists were able to measure the speed of light much more easily. In 1972, the National Institute of Standards and Technology discovered that the actual speed of light was 299,792,458 meters per second, or 186,282 miles per second (just 189 miles different than Foucault's measurement). Because of these new results, the General Conference of Weights and Measures fixed the meter as the distance light travels in 1/299,792,458 of a second.
However, the speed of light does vary, depending on the medium. Albert Einstein proved that light is the fastest moving thing in a vacuum, with its speed being roughly 186,000 miles per second. In water, the speed of light slows to 140,000 miles per second. Its speed is 124,000 per second in glass. Through a diamond, the speed of light is 77,500 miles per second.
>>>>>mAAUng GaBiE sA tanAn.......espEcIaLly ni mAam...
""ligh is also electromagnetic spectrum that made up of different speeds of wavelengths and include ultraviolet and infrared rays. There are several different kinds of electromagnetic waves that move at the speed of light. Many scientists worked to discover the actual speed of light.......
""After the discovery of infrared light by Herschel, a Danish physicist named Hans Christian Oersted found an electrical current that could change the direction of a compass' needle. André-Marie Ampère also found that different electrical currents could also attract or repel one another. It was in 1865 when James Clerk Maxwell proposed the idea of electromagnetism. He showed that electricity and magnetism were closely related and if made to surge back and forth, could produce alternating electromagnetic waves, which would move at the speed of light. Maxwell then concluded that light itself must be an electromagnetic wave.
Infrared, visible light, and ultraviolet are not the only types of waves. Further down past infrared lay microwaves, radar, television waves, and radio waves. Microwaves are thought to have been released during the Big Bang, which could have started the universe. These slow waves are used in microwave ovens to heat food by changing the alignment of water molecules. Even slower are radar waves. Radar is an acronym for "Radio Detection and Ranging." Radar scanners send out short radio waves and detect the echoes from objects in their path. Further down are television waves. These waves send out sound and pictures to our TV sets. The slowest known waves of all are radio waves. Not only produced by radio stations, radiowaves are sent out by stars and galaxies.
At the ultraviolet end of the spectrum are three other types of waves, all with higher frequencies than ultraviolet. Directly in front of ultraviolet is X-rays. While X-rays can pass through the soft parts of our bodies, they can not penetrate bone. This is why they are used today to take pictures of broken bones. Gamma rays are radioactive and are released by certain atomic nuclei. With their large amounts of energy they are able to penetrate metal and concrete and kill living cells. This type of wave is released by nuclear bombs, causing multitudes of destruction. The highest-energy and most frequent waves are cosmic rays. They are made up of particles of atomic nuclei, electrons, and gamma rays. The earth's atmosphere protects from these waves which come from outer space.
Though it may not seem like it, light takes time to get from one place to another. The light we see from the stars at night was emitted from the star a very long time ago. In fact, the star might have burned out by the time its rays reach us, but we can't see it because it takes times to reach our solar system.
The first clue towards the speed of light came from outer space, from the planet Jupiter. In 1676, Danish astronomer Olaus Roemer observed the difference in peroids that Jupiter's moons had to the Earth's orbit. He realized that the light reflected off the moons had a different amount of light to travel depending on the Earth's position. Using this knowledge, he used mathematics to estimate that the speed of light was 136,646 miles per second. Unfortunately, Roemer didn't know that his calculations were too low, but his work was a large accomplishment for his time.
Armand Fizeau made the first land-based estimate in 1849. Fizeau set up an experiment where he placed a light five and a half miles away from a mirror. In front of the light, he set up a wheel with toothed edges. When the light would shine, it would pass through the gap between two teeth. The mirror would reflect the beam back and would shine through the next gap between the teeth. Fizeau could then estimate the speed of light from the speed at which the toothed wheel was moving. He measured the speed at 194,410 miles per second.
A year later in 1850, Léon Foucault made some changes to Fizeau's experiment. Instead of using a toothed wheel, Foucault replaced it with a spinning mirror. The light would shine onto the spinning mirror and be reflected towards a series of stationary mirrors. By measuring the amount of distance the light had to travel and knowing how fast the mirror was spinning, Foucault figured the speed of light to be 185,093 miles per second. Foucault's results were very close to the actual speed of light.
Once lasers were invented, scientists were able to measure the speed of light much more easily. In 1972, the National Institute of Standards and Technology discovered that the actual speed of light was 299,792,458 meters per second, or 186,282 miles per second (just 189 miles different than Foucault's measurement). Because of these new results, the General Conference of Weights and Measures fixed the meter as the distance light travels in 1/299,792,458 of a second.
However, the speed of light does vary, depending on the medium. Albert Einstein proved that light is the fastest moving thing in a vacuum, with its speed being roughly 186,000 miles per second. In water, the speed of light slows to 140,000 miles per second. Its speed is 124,000 per second in glass. Through a diamond, the speed of light is 77,500 miles per second.
light is life....(thats for sure)
SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light. Earth would not have any life on it without the Sun’s energy, which reaches Earth in the form of heat and light. This energy warms our days and illuminates our world. Green plants absorb sunlight and convert it to food, which these plants then use to live and grow. In this process, the plants give off the oxygen that animals breathe. Animals eat these plants for nourishment. All plant and animal life relies on the Sun’s presence. Light is also essential for the survival of most animal species. The Sun also provides—directly or indirectly—much of the energy on Earth that people use for fuel ( Solar Energy) Devices called solar cells turn sunlight into electricity. Sunlight can heat a gas or liquid, which can then be circulated through a building to heat the building. The energy stored in fossil fuels originally came from the Sun. Ancient plants used sunlight as fuel to grow. Animals consumed these plants. The plants and animals stored the energy of sunlight in the organic material that composed them. When the ancient plants and animals died and decayed, this organic material was buried and gradually turned into the petroleum, coal, and natural gas people use today. The Sun’s energy produces the winds and the movements of water that people harness to produce electricity (see Wind Energy; Water Power). The Sun heats Earth’s oceans and land, which in turn heat the air and make it circulate in the atmosphere as wind. The Sun fuels Earth’s water cycle, evaporating water from the oceans, seas, and lakes. This water returns to the ground in the form of precipitation, flowing back to the oceans through the ground and in rivers. The energy of water’s motion in rivers can be harnessed with dams..... LIGHT as medicine.,., Niels Ryberg Finsen (1860-1904), Danish physician and Nobel Prize winner who made important discoveries regarding the use of light waves in the treatment of disease. Finsen was born in Tórshavn, the capital of the Faeroe Islands, a part of Denmark located north of the British Isles. After completing his early schooling in Denmark and in Reykjavík, Iceland, Finsen attended the University of Copenhagen in Denmark, receiving his medical degree in 1891. He then taught anatomy in the university's Department of Surgery, leaving in 1893 to devote himself full-time to studying “phototherapy,” or the therapeutic effects of light. In 1896 he established the Light Institute in Copenhagen. For his groundbreaking contributions to the new field of phototherapy, Niels Finsen received the 1903 Nobel Prize in physiology or medicine. Even as a child, Finsen had been fascinated by the effects of sunlight on living things. His research as an undergraduate included experiments in which he observed how sunlight affected the tissue of insects, tadpoles, and other animals. Later Finsen decided to turn his efforts toward the treatment of human diseases. In 1893 he began to study the use of filtered sunlight in the treatment of skin lesions caused by smallpox, a viral disease. Red light—that is, light from the red end of the spectrum—with its harmful heat rays filtered out, proved successful in promoting the healing of smallpox lesions. After publishing key papers on phototherapy in 1893 and 1894, Finsen began research into the treatment of lupus vulgaris, a disfiguring skin disease caused by bacteria. Finsen had noted the findings of previous researchers, who discovered that light could kill bacteria. Focusing an artificial light through a prism, Finsen exposed diseased tissue to high concentrations of ultraviolet light. The method proved highly effective in treating lupus vulgaris. Finsen established his Light Institute in Copenhagen, where hundreds of lupus vulgaris patients were successfully treated over the next few years. The use of ultraviolet light remained the central treatment for lupus vulgaris for decades.
bow!!!!!!datz all
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Neccessary Poetry
valuability is brought about. by defectiveness. and you'll get used to it ... you're the light i've been seeking. you were mind boggling. you were intense ...
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NASM Oral History Project, Webb #7
... strengthened as test after test proved the valuability of the system. ... Apollo 11, and could then be judged in the light of the success of 2 landings. ...
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Lego nostalgia part 1 | nicjasno.com
... on peeron.com the ratio between and valuability of parts you get for the money ... The car will be a sports car, 2/3 the length of the challenger, and very light. ...
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VN Boards - Skald Report - Post 1.62
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[PDF] Introduction and Purposes
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... Resource Inherently Valuability Rating. 24. ... Normal light contains a range of wavelengths familiar to us as ... those that are reflected by visible light. ...
califonborough-nj.org/files/.../ERI Narrative Issue 1.pdf
The Beanie Baby Secondary Market
... limited amount of time, more valuability should eventually increase to the product. ... like wingless Quackers, Black Batty, Light Blue Peanut, and ty-dyed ...
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PSP Crazy - Article: The History of Console Piracy and how it affects ...
By Vahid Mirjamali (Owner of PSPcrazy.com) ... compare to the game satisfaction and valuability.If the game is really gud,i ... Grow up people and see the light...
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21. VI. E. VALUABILITY .25. VII. R. ESULTS : O. PPORTUNITIES AND. C ... explicit poverty strategy in light of the controversial nature of the issue and the ...
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Personal approach to Symbolic reality
... within history, whole societal movements can be reflective of its light. ... The life pierced by call of death discovers valuability. ...
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thats all...
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Neccessary Poetry
valuability is brought about. by defectiveness. and you'll get used to it ... you're the light i've been seeking. you were mind boggling. you were intense ...
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NASM Oral History Project, Webb #7
... strengthened as test after test proved the valuability of the system. ... Apollo 11, and could then be judged in the light of the success of 2 landings. ...
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[PDF] Introduction and Purposes
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... Resource Inherently Valuability Rating. 24. ... Normal light contains a range of wavelengths familiar to us as ... those that are reflected by visible light. ...
califonborough-nj.org/files/.../ERI Narrative Issue 1.pdf
The Beanie Baby Secondary Market
... limited amount of time, more valuability should eventually increase to the product. ... like wingless Quackers, Black Batty, Light Blue Peanut, and ty-dyed ...
www.geocities.com/collectiblezz/SecondaryMarket.html - Cached
PSP Crazy - Article: The History of Console Piracy and how it affects ...
By Vahid Mirjamali (Owner of PSPcrazy.com) ... compare to the game satisfaction and valuability.If the game is really gud,i ... Grow up people and see the light...
www.pspcrazy.com/?page=Articles&action=showarticle&id=201 - 220k - Cached
[PDF] RE-288 Poverty Reduction and the IDB: An Evaluation of the Bank's ...
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21. VI. E. VALUABILITY .25. VII. R. ESULTS : O. PPORTUNITIES AND. C ... explicit poverty strategy in light of the controversial nature of the issue and the ...
enet.iadb.org/idbdocswebservices/idbdocsInternet/...?docnum=320191
Personal approach to Symbolic reality
... within history, whole societal movements can be reflective of its light. ... The life pierced by call of death discovers valuability. ...
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Upon the subject of the liturgical use of lights, as an adjunct of the services of the Church, something has already been said under such headings as ALTAR (IN LITURGY), sub-title Altar-Candles; BENEDICTION OF THE BLESSED SACRAMENT; CANDLES; CANDLESTICKS; LAMPS AND LAMPADARII. The present article will be concerned only with the more general aspect of the question, and in particular with the charge so often levelled against Catholicism of adopting wholesale the ceremonial practices of the pagan world.
How far the use of lights in the daytime as an adjunct of the Liturgy can be traced back to the second or third century A. D. is not quite easy to decide. On the one hand, there seems to be some evidence that the Christians themselves repudiated the practice. Although Tertullian ("Apol.", xlvi and xxxv; "De Idololat.", xv) does not make any direct reference to the use of lights in religious worship, still he speaks in strong terms of the uselessness of burning lamps in the daytime as an act of piety towards the emperors. This would be somewhat inconsistent, if the Christians themselves had been open to the same reproach. Moreover, several of the Fathers of the fourth century might seem to be more explicit in their condemnation of a display of lamps. For example, about the year 303, Lactantius writes: "They [the pagans] burn lights as to one dwelling in darkness. . . Is he to be thought in his right mind who offers for a gift the light of candles and wax tapers to the author and giver of light? . . . But their Gods, because they are of the earth, need light that they need not be in darkness" ("Institut. Div.", VI, ii). In like manner, St. Gregory of Nazianzus, towards the end of the same century, observes: "Let not our dwelling-place blaze with visible light and resound with minstrelsy, for this indeed is the custom of the Greek holy-month, but let us not honour God with these things and exalt the present season with unbecoming rites, but with purity of soul and cheerfulness of mind and with lamps which enlighten the whole body of the Church, i.e. with divine contemplations and thoughts" (Orat., v, 35). The rhetorical character of such passages makes it dangerous to draw inferences. It may well be that the writers are merely protesting against the illuminations which formed part of the ordinary religious cultus of the emperors, and wish to state forcibly the objections against a similar practice which was beginning to find favour among Christians. It is, at any rate certain that even earlier than this the liturgical use of lights must have been introduced. The decree of the Spanish Council of Illiberis, or Elvira (about A. D. 305), is too obscure to afford a firm basis for argument (see Hefele-Leclercq, "Hist. des Conciles", I, 212). Still this prohibition, "that candles be not lighted in a cemetery during the day, for the spirits of the saints ought not to be disquieted" (can. xxxiv), at least shows that the practice — which we know to have been long in use among pagans — of burning lights, for some symbolical or superstitious reason, even in the daytime, was being adopted among the Christians also. To discuss in detail the perplexing and seemingly inconsistent references of St. Jerome to the use of lights would not be possible here. But two facts stand out clearly:
(1) that he admitted the existence of a pretty general custom of burning candles and lamps in honour of the martyrs, a custom which he apologizes for without unreservedly approving it; and
(2) that the saint, though he denies that there is any general practice among the Christians of burning lights during the daytime, still admits at least some instances of a purely liturgical use of light.
Thus he says: "Apart from honouring the relics of martyrs, it is the custom, through all the Churches of the East, that when the gospels are to be read lights are kindled, though the sun is already shining, not, indeed, to dispel darkness, but to exhibit a token of joy . . . and that, under the figure of bodily light, that light may be set forth of which we read in the psalter 'thy word is a lamp to my feet and a light to my paths" (C. Vigilantium, vii). This testimony is particularly valuable because it so clearly refutes any exclusively utilitarian view of the use of lights in the churches.
From Eusebius, St. Paulinus of Nola, the "Peregrinatio Ætheriæ" (Pilgrimage of Ætheria), and other authorities, we have abundant evidence that the Christians of the fourth century, and probably earlier still, upon Easter eve and some other solemn festivals, made a great display of lamps and candles of all kinds. Moreover, this does not seem to have been confined to the nocturnal vigil itself, for St. Paulinus in describing the feast of St. Felix to whom his church was dedicated, tells us in verse how "the bright altars are crowned with lamps thickly set. Lights are burnt, odorous with waxed papyri. They shine by night and day; thus night is radiant with the brightness of the day, and the day itself, bright in heavenly beauty, shines yet more with light doubled by countless lamps" ("Poem.", xiv, "Nat." iii, in P. L., LXI, 467). Still this poetical language may very possibly mean no more than that in a rather dark church it was found desirable to keep the lamps burning even in daytime upon great festivals, when there was a large concourse of people. It tells us nothing of any use of lights which is liturgical in the stricter sense of the word. The same may be said of various references to the festal adornment of churches with lamps and candles which may be found in the writings of the Christian poet Prudentius (cf. P. L., LIX, 819, 829; and LX, 300). Still, when we find in the newly discovered "Testament of our Lord" (l. 19) an injunction regarding church buildings, that "all places should be lighted both for a type and also for reading", it seems clear that St. Jerome was not alone in attaching a mystical significance to the use of lights. Hence we may infer that before the days (about A. D. 475) of the liturgical homilist Narsai (see LAMPS AND LAMPADARII) the use of lamps and candles around the altar during the Liturgy had become universal.
It should be added that no great importance can be attached to the mention by St. Paulinus of Nola, of "a perpetual light" in the church ("continuum scyphus argenteus aptus ad usum"; cf. P. L., LXI, 539). This certainly cannot be assumed to have been intended as a mark of respect to the Blessed Sacrament reserved for the sick. In the days before the invention of matches the continuance of some source of fire from which a light could be readily obtained was a matter of great convenience. Such a perpetual light seems to have been usually kept up, then as now, in Jewish synagogues (cf. Exodus 27:20; Leviticus 24:2), but it was only the later Talmudists who discovered in this a purpose of honouring the Torah, or Books of the Law, preserved in the Ark. The same utilitarian design probably underlay any Christian practice, which, after all, is not very widely attested, of keeping a light perpetually burning in the church.
But to return to the liturgical use of lights in the stricter sense, there are not wanting many considerations to suggest that, despite the lack of direct evidence, this practice is probably of very much older date than the fourth century. To begin with, the seven-branched "candlestick", or more accurately lamp-stand, was a permanent element in the Temple ritual at Jerusalem and more than one Jewish festival (e.g. the Dedication feast and that of Tabernacles), was marked by a profuse use of lights. Moreover, the Apocalypse (i, 12; iv, 5; xi, 4), in the prominence which it gives to the mention of candlesticks and lamps, is probably only echoing the more or less liturgical conceptions already current at the time. Again, the fact that the Liturgy was at first no doubt celebrated in the evening (cf. 1 Corinthians 11:21), as also the necessity that the faithful should often assemble by stealth (as in the catacombs) or in the early hours of the morning (cf. Pliny, "Epp", X, n. 97 — ante lucem convenire; and Tertullian, "De Cor.", iii — antelucanis cœtibus), render it highly probable that artificial light must have come to be regarded as an ordinary adjunct of the Liturgy. Hence the use of lamps and candles was probably continued even when not actually needed, just as, in more modern days, the bishop's bugia, which in the beginning served an entirely practical purpose, has come in time to be purely ceremonial. It is also noteworthy that early representations of the Last Supper nearly always give prominence to the lamp, while something of the same kind obtains in the first rude sketches of Christian altars. In any case, lamps and chandeliers are conspicuous amongst the earliest recorded presents to churches (see the "Liber Pontificalis", ed. Duchesne, passim; and cf. the inventory of Cirta, A. D. 303, in Morcelli, "Africa Christiana", II, 183; and Beissel, "Bilder aus der altchrist. Kunst", 247).
Both in ancient and modern times, the reproach has been leveled against the Church that in her ceremonial use of lights she has taken over without scruple the sensuous and often idolatrous practices of paganism. For this charge there is very little real justification. To begin with, it must be evident that such simple elements as light, music, rich attire, processions, ablutions, and lustrations, flowers, unguents, incense, etc., belong, as it were, to the common stock of all ceremonial, whether religious or secular. If there is to be any solemnity of external worship at all it must include some at least of these things, and whether we turn to the polytheistic ritual of ancient Greece and Rome, or to the nations of the far East, or to the comparatively isolated civilizations of the aborigines of Mexico and Peru, human striving after impressiveness is found to manifest itself in very similar ways. A multiplicity of lights is always in some measure joyous and decorative, and it is a principle taught by everyday experience that marks of respect which are shown at first with a strictly utilitarian purpose are regarded in the end as only the more honorific if they are continued when they are plainly superfluous. Thus an escort of torches or candle-bearers, which is almost a necessity in the dark, and is a convenience in the twilight, becomes a formality indicative of ceremonious respect if maintained in the full light of day. Again, since the use of lights was so familiar to Jewish ritual, there is no sufficient ground for regarding the Christian Church as in this respect imitative either of the religions of Greece and Rome or of the more oriental Mithra worship. At the same time, it seems probable enough that certain features of Christian ceremonial were directly borrowed from Roman secular usages. For example, the later custom that seven acolytes with candlesticks should precede the pope, when he made his solemn entry into the church, is no doubt to be traced to a privilege which was common under the Empire of escorting the great functionaries of the State with torches. This right is expressly recognised in the "Notitia Dignitatum", but it may also be found in embryo at an earlier date, when the Consul Duilius for his victory over the Carthaginians, in the third century before Christ, obtained the privilege of being escorted home by a torch and a flute player. But granting, as even so conservative an historian as Cardinal Baronius is fully prepared to grant, a certain amount of direct borrowing of pagan usages, this is no subject of reproach to the Catholic Church. "What", he says, "is to prevent profane things, when sanctified by the word of God, being transferred to sacred purposes? Of such pagan rites laudably adopted for the service of the Christian religion we have many examples. And with regard more especially to lamps and candles, of which we are now speaking, who can reasonably find fault if those same things which were once offered to idols are now consecrated to the honour of the martyrs? If those lamps which were kindled in the temples on Saturdays — not as though the gods needed light, as even Seneca points out (Ep. xv, 66), but as a mark of veneration — are now lighted in the honour of the Mother of God? If the candles which were formerly distributed at the Saturnalia are now identified with the feast of the Purification of our Lady? What, I ask, is there so surprising if holy bishops have allowed certain customs firmly rooted among pagan peoples, and so tenaciously adhered to by them that even after their conversion to Christianity they could not be induced to surrender them, to be transferred to the worship of the true God?" (Baronius, "Annales", ad ann. 58, n. 77).
With regard to the use of lights in direct connexion with the Holy Sacrifice of the Mass, we find the whole system of portable lights elaborated in the earliest of the "Ordines Romani". Indeed, St. Jerome's plain reference, already quoted, to the carrying of lights at the Gospel, seems probably to take the practice back to at least three hundred years earlier, even if we may not appeal, as many authorities have done, to the words of the Acts of the Apostles (xx, 7-8): "And on the first day of the week, when we were assembled to break bread, Paul discoursed with them. . . . And there were a great number of lamps in the upper chamber where we were assembled." It does not seem to have been customary to place lights upon the altar itself before the eleventh century, but the "Ordines Romani" and other documents make it clear that, many centuries before this, lights were carried in procession by acolytes (see ACOLYTE), and set down upon the ground or held in the hand while Mass was being offered and the Gospel read. A decree of the so-called Fourth Council of Carthage directs that in the ordination of an acolyte a candlestick is to be given him, but this collection of canons does not belong, as was once supposed, to the year 398, but to the time of St. Cæsarius of Arles (about A. D. 512). A little later, i.e. in 636, St. Isidore of Seville (Etymol., VII, xii, n. 29) speaks quite explicitly on the point: "Acolytes", he says, "in Greek, are called Ceroferarii in Latin, from their carrying wax candles when the Gospel is to be read or the sacrifice to be offered. For then lights are kindled by them, and carried, not to drive away darkness, as the sun is shining, but for a sign of joy, that under the form of material light may be represented that Light of which we read in the Gospel: That was the true light." It was only at a later date that various synodal decrees required the lighting of first one candle, and afterwards of two, during the time of the celebration of Mass.
The use of lights in baptism, a survival of which still remains in the candle given to the catechumen, with the words: "Receive this burning light and keep thy baptism so as to be without blame", etc., is also of great antiquity. It is probably to be connected in a very immediate way with the solemnities of the Easter vigil, when the font was blessed, and when, after careful preparation and a long series of "scrutinies", the catechumens were at last admitted to the reception of the Sacrament. Dom Morin (Revue Bénédictine, VIII, 20; IX, 392) has given excellent reason for believing that the ceremonial of the paschal candle may be traced back to at least the year 382 in the lifetime of St. Jerome. Moreover the term photisthentes (illuminati), so constantly applied to the newly baptized in early writings, most probably bears some reference to the illumination which, as we know from many sources, marked the night of Holy Saturday. Thus St. Ambrose (De Laps. Virg., v, 19), speaking of this occasion, mentions "the blazing light of the neophytes", and St. Gregory of Nazianzus, in his great "Sermon on Holy Baptism", tells the candidates that "the lamps which you will kindle are a symbol of the illumination with which we shall meet the Bridegroom, with the lamps of our faith shining, not carelessly lulled to sleep" (Orat., xl, 46; cf. xlv, 2).
Again, the pagan use of lights at funerals seems to have been taken over by the Church as a harmless piece of ceremonial to which a Christian colour might easily be given. The early evidence upon this point in the writings of the Fathers is peculiarly abundant, beginning with what Eusebius tells us of the lying in state of the body of the Emperor Constantine: "They lighted candles on golden stands around it, and afforded a wonderful spectacle to the beholders, such as never was seen under the sun since the earth was made" (Vita. Const., iv, 66). Similarly, St. Jerome tells us of the obsequies of St. Paula in 386: "She was borne to the grave by the hands of bishops, who even put their shoulders under the bier, while other pontiffs carried lamps and candles before her" (Ad Eustoch., ep. cviii, n. 29). So, again in the West, at the funeral of St. Germanus of Auxerre, "The number of lights beat back the rays of the sun, and maintained their brightness even through the day" (Constantius, "Vita S. Germani", II, 24).
It is also certain that, from a very early period, lamps and candles were burnt around the bodies, and then, by a natural transition, before the relics, of the martyrs. How far this was merely a development of the use of lights in funerals, or how far it sprang from the earlier pagan custom of displaying a number of lamps as a tribute of honour to the emperor or others, it is not easy to decide. The practice, as we have seen, was known to St. Jerome, and is with some reservation defended by him. This burning of lights before shrines, relics, and statues naturally assumed great developments in the Middle Ages. Bequests to various "lights" in the churches which the testator desired to benefit generally occupy a considerable space in medieval wills, more particularly in England.
Upon the symbolism of ecclesiastical lights much has been written by medieval liturgists from Amalarius downwards. That all such lights typify Jesus Christ, Who is the Light of the World, is a matter of general agreement, while the older text of the "Exultet" rendered familiar the thought that the wax produced by virgin bees was a figure of the human body which Christ derived from His immaculate Mother. To this it was natural to add that the wick was emblematic of Christ's human soul, while the flame represented His Godhead. But the medieval liturgists also abound in a variety of other symbolic expositions, which naturally are not always quite consistent with one another.
THE IMPORTANCE OF LIGHT
Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
For diurnal species (species that are active during the day), light is important for many reasons. Obviously, it is required for vision, and most birds have highly developed sight. For many species of animals, full-spectrum light is required for the conversion of cholesterol to vitamin D. Light and its changing cycles -- photoperiodicity is used by animals to synchronize their biological clocks. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals.
Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom. The extremely large eye leaves little room in the head for anything else. For example. an ostrich eye is 2 inches in diameter, an owl eye is one-third the entire head weight, and the buzzard eye has four times the visual acuity (sharpness) of a human eye.
Photoperiodicity has long been studied in birds as a means of inducing reproduction. Day length is detected by the pineal gland. The adrenal gland is located in the brain between the cerebella hemispheres and the cerebellum. It has numerous functions, one of which is photoreceptor and regulator of circadian rhythms. Some photoreceptors are located deep within the brain and are not dependent upon the eyes for photoreception. The hormones of the pineal gland (melatonin primarily) affect sleep, behavior and brain electrical activity. There is also evidence that melatonin influences reproductive hormonal cycles by affecting the pituitary gland. This has been very important in inducing poultry to lay eggs and to maximize egg production.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
Numerous breeders of exotic birds have used changing the day length in an attempt to manipulate breeding. however, few controlled studies have been conducted to assess its effects. Work at the department of avian sciences at the University of California at Davis and elsewhere demonstrated that long day lengths stimulate reproductive activity in cockatiels and blossom-headed parakeets. In general. birds must be exposed to short day lengths (10 hours of light, 14 hours of dark). before they can respond to long day lengths. The length of the photoperiod that may be stimulatory can only be determined experimentally for each species, but it may range from 13 to 17 hours. Ideally, it would increase gradually. Many birds will become unresponsive to this stimulus after prolonged! light stimulation. Work at UC Davis showed that cockatiels became resistant after two clutches. For pet birds, the sometimes prolonged or erratic photoperiods that they are exposed to in the home may affect them behaviorally. A bird exhibiting signs of sexual over stimulation or frustration (such as plucking) may respond to a shortened day length.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass.
Vitamin D can be toxic, so be careful not to over supplement. Birds housed outdoors do not need supplemental vitamin D. Special Effects Light affects the health and well being of people and animals in numerous ways. Dr. John Ott did some of the pioneering studies in the 1960s and 1970s. He conducted numerous studies on the effects of light on plants and animals. He utilized time-lapse photography to demonstrate plant growth and the effects of limiting the photo spectrum. Working with fluorescent lights, such as cool white, daylight white. and warm white bulbs that were limited in spectrum, some plants would not flower properly. By using light filters to further limit the light spectrum he could produce signs suggestive of viral disease in plants. He conducted similar studies in mice and found that deprivation of part of the light spectrum could produce loss of fur, skin disease, curling and loss of the tail, and inflammation of the heart muscle (myocarditis). It also affected the behavior of the mice, making some aggressive and agitated. In studies of children in school where curtains were closed and limited spectrum fluorescent lights were used, children were hyperactive and inattentive. This behavior was corrected when the lights were changed and the curtains were opened. He also equated malillumination with malnutrition.
A recent Wall Street Journal report showed how light is being used to enhance human well being. Prior to the invention of the electric light in 1879, buildings were designed with an emphasis on placement of windows to enhance natural lighting. As architects relied more on electric lighting, natural lighting of buildings was reduced. The need for energy efficiency has again affected how we design our indoor spaces for light. Recently, European countries have begun to require that a percentage of a building's light come from outdoors -- 37 percent in the Netherlands, for example.
According to a report by the Rocky Mountain Institute in Snowmass, Colorado, increasing daylight results in fewer days lost to absenteeism and fewer errors and defects. The report, "Greening the Building and the Bottom Line", cites improved heating and cooling in eight commercial buildings thanks to natural light. Installation of special skylights and-tall windows improved lighting and cut lighting costs by up to 75 percent. An unexpected effect was a 15-percent drop in employee absenteeism, as well as increased productivity and sales.
People living in northern cities that are overcast for long periods of time and receive little sunshine typically report depression. Birds housed continually indoors may also suffer from depression. Taking your wing-clipped bird outdoors for a bath in the sun is great for its plumage and its spirits. If you have the opportunity to see the plumage quality of birds housed outdoors that has access to rain and sunlight, you will be a believer.
Try to place your bird near a sunny window, but make sure it can move out of direct sunlight when it wants. A useful substitute may be a full-spectrum fluorescent bulb with the fixture close enough to the bird to provide the UV spectrum. Ideally, the bulb should be within a foot or two of the bird to provide benefits.
Remember that the capability of the bulb to produce UV does not last for the life of the bulb. The bulb can still be used for general lighting purposes after it is no longer producing full-spectrum light. Certainly, we must not forget the potential hazard of excessive UV exposure, such a skin cancer and eye disease.®
Lighting includes both artificial light sources such as lamps and natural illumination of interiors from daylight. Lighting represents a major component of energy consumption, accounting for a significant part of all energy consumed worldwide. Artificial lighting is most commonly provided today by electric lights, but gas lighting, candles or oil lamps were used in the past, and still are used in certain situations. Proper lighting can enhance task performance or aesthetics, while there can be energy wastage and adverse health effects of lighting. Indoor lighting is a form of fixture or furnishing, and a key part of interior design. Lighting can also be an intrinsic component of landscaping.
Low-intensity lighting and haze in a concert hall allows laser effects to be visibleContents [hide]
1 Fixtures
1.1 Types
1.2 Methods
2 Vehicle use
3 Lamps
4 Design
5 Measurement
6 Energy consumption
7 Health effects
8 Environmental issues
9 Military use
10 Professional organizations
11 See also
11.1 Inventors
11.2 Lists
12 References
13 External links
Light, or visible light, is electromagnetic radiation of a wavelength that is visible to the human eye (about 400–700 nm). In a scientific context, the word light is sometimes used to refer to the entire electromagnetic spectrum. Moreover, in optics, the term "visible light" refers to electromagnetic radiation with wavelengths of ~300 nm (near UV) through ~1400 nm (near infrared). [1] Light is composed of elementary particles called photons.
Three primary properties of light are:
Intensity;
Frequency or wavelength and;
Polarization.
Light can exhibit properties of both waves and particles. This property is referred to as wave–particle duality. The study of light, known as optics, is an important research area in modern physics.
Contents [hide]
1 Speed of light
2 Refraction
3 Optics
4 Light sources
5 Theories about light
5.1 Indian theories
5.2 Greek and Hellenistic theories
5.3 Optical theory
5.4 The 'plenum'
5.5 Particle theory
5.6 Wave theory
5.7 Electromagnetic theory
5.8 The special theory of relativity
5.9 Particle theory revisited
5.10 Quantum theory
5.11 Wave–particle duality
5.12 Quantum electrodynamics
6 Light pressure
7 Spirituality
8 References
9 See also
10 External links
;quail 1st assignment..,
-> Is LIGHT valuable?
-> answer:
The quality of light is important but also the quantity and the length are. For the quality, the visible to human-eye light spectrum is composed of all the seven (7) rainbow colors. But the main colors are red, green and blue. Those useful to plants are blue and red spectrum. The quantity refers too how much light is present and the length refers to the time of exposition to light.
The blue spectrum of light will interact with the plant by inducing foliage composition and creating a dense plant. The red spectrum will induce growth but also flowering. The role of the green spectrum with plants is undetermined. The best source of light is still free, because it is the sun. The sun produces an almost equal amount of red, green and blue rays.
Two phenomena are also associated with plant and light. They are called phototropism and photoperiodism. The first one can be observe on sunflowers. Sunflower will turn wherever the sun is. They are not searching for the sun, but the best source of light.
The last of the phenomena, photoperiodism, is how the plants react to the cycle of day and night, presence of light and lack of light. The successive periods are in direct link with the seasons. Amount of light and day lentgh vary with the seasons, so in fall when temperature drop and day are getting shorter, leaves are dropping and plants will go dormant. The contrary is happening in spring when days are getting longer and temperature increases, plants goes out of dormancy and activate its development. Playing with this phenomenon is a technique used by flowers producers. They induce flowering at a certain period of the year, like Easter or Christmas by giving no more then 8-9 hours of sunlight per day. To induce the flowering, they gradually bring back the exposition to light to an average of 12-16 hours of light a day. Of course this can be used on flowering bonsai tree.As we see, light is the main actor in plants development. But aside the technical side of things, what about direct effect of light or lack of light on our bonsai? Some plants are less demanding in term of light, but tree, hence bonsai, will require all the light they can get.
First, in situation of lack of light, the plant will react by producing a “leggy” plant. Leggy plants are those with long internodes on the trunk and branches. This is a result of plants trying to reach the light above the canopy of what it think is a shade create by taller tree’s. We don’t want this to happen to our miniature tree.
thats all........
* end *
;quail 1st assignment...
-> Is LIGHT valuable?
->answer:
Light is essential to maintaining normal, healthy physiology. Exposure to sunrise is key to synchronizing our internal body cycles to the external world (so we sleep when it is dark and are alert during the day).
Modern industrial society began to tamper with this system, though. The loss of natural light - in dark apartments, in the workplace, on shift work, etc. - creates a state of light deprivation, making us vulnerable to depressed mood, sleep problems, fatigue, ability to concentrate, and more. Nature, too, posed a new problem when humans began to migrate north, where winter nights are long and dark.
Light levels as measured in lux vary greatly between indoor and outdoor lighting. You can see from the chart below how easy it is to become light deprived in our modern, indoor society.
Indoor Lighting
Indoors at home 200-500 lux
Indoors at office 400-700 lux
Springtime Lighting on a Clear Day
5:55 Sunrise 750 lux
6:10 a.m. 2,500 lux
6:20 a.m. 5,000 lux
6:40 a.m. 10,000 lux
12:00 Noon 81,000 lux
5:10 p.m. 10,000 lux
5:30 p.m. 5,000 lux
5:40 p.m. 2,500 lux
5:55 Sunset 750 lux
Although researchers do not have firm numbers, a lot of people are light deprived. Symptoms of light deprivation include:
Feeling depressed or moody during the fall and winter
Fatigue, lack of energy, and difficulty getting up in the morning
Problems getting things done (lack of motivation)
Reduced social contact (often reduced sexual interest)
Cravings for carbohydrates and weight gain
Surveys suggest that as many as 1 in 20 people experience full-blown winter depression in the northern hemisphere, and three times as many experience winter doldrums. Far larger numbers experience nonseasonal depression at some point in their lives, often for years at a time. With the recent findings that light therapy can also work for nonseasonal depression - light itself or in combination with drugs, the size of the responsive population multiplies.
thats all........
thank u!!!!!!!!!!!!!
Light is valuabe.
yes!Light is valuable, because light is a universal substance that God used to create both the spiritual and the material world. Modern science has revealed that the material universe is made from energy. Light is one form of energy, and all energy is vibration.
Without light, there would be no sight. The visual ability of humans and other animals is the result of the complex interaction of light, eyes and brain. We are able to see because light from an object can move through space and reach our eyes. Once light reaches our eyes, signals are sent to our brain, and our brain deciphers the information in order to detect the appearance, location and movement of the objects we are sighting at. The whole process, as complex as it is, would not be possible if it were not for the presence of light. Without light, there would be no sight.
Are you somewhere inside a home? Look around. Wherever you are, there is at least one element whose presence can unfailingly be predicted. Light. There must be a window or a light fixture. The room is useless without light. When a room strikes you as pleasant to sit in, beautiful to look at, or efficient to work in, be attentive to its lighting. The placement and size of windows, or the type, position, and brightness of light fixtures, combine to create a certain mood, an atmosphere. Human beings are very sensitive to light: we easily perceive the impact that relatively small changes in lighting have on the overall feel of a room.
only here maam!thank you..
Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
For diurnal species (species that are active during the day), light is important for many reasons. Obviously, it is required for vision, and most birds have highly developed sight. For many species of animals, full-spectrum light is required for the conversion of cholesterol to vitamin D. Light and its changing cycles -- photoperiodicity is used by animals to synchronize their biological clocks. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals.
Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom. The extremely large eye leaves little room in the head for anything else. For example. an ostrich eye is 2 inches in diameter, an owl eye is one-third the entire head weight, and the buzzard eye has four times the visual acuity (sharpness) of a human eye.
Photoperiodicity has long been studied in birds as a means of inducing reproduction. Day length is detected by the pineal gland. The adrenal gland is located in the brain between the cerebella hemispheres and the cerebellum. It has numerous functions, one of which is photoreceptor and regulator of circadian rhythms. Some photoreceptors are located deep within the brain and are not dependent upon the eyes for photoreception. The hormones of the pineal gland (melatonin primarily) affect sleep, behavior and brain electrical activity. There is also evidence that melatonin influences reproductive hormonal cycles by affecting the pituitary gland. This has been very important in inducing poultry to lay eggs and to maximize egg production.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
Numerous breeders of exotic birds have used changing the day length in an attempt to manipulate breeding. however, few controlled studies have been conducted to assess its effects. Work at the department of avian sciences at the University of California at Davis and elsewhere demonstrated that long day lengths stimulate reproductive activity in cockatiels and blossom-headed parakeets. In general. birds must be exposed to short day lengths (10 hours of light, 14 hours of dark). before they can respond to long day lengths. The length of the photoperiod that may be stimulatory can only be determined experimentally for each species, but it may range from 13 to 17 hours. Ideally, it would increase gradually. Many birds will become unresponsive to this stimulus after prolonged! light stimulation. Work at UC Davis showed that cockatiels became resistant after two clutches. For pet birds, the sometimes prolonged or erratic photoperiods that they are exposed to in the home may affect them behaviorally. A bird exhibiting signs of sexual over stimulation or frustration (such as plucking) may respond to a shortened day length.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass.
Yes, LIGHT is valuable because it's the reason why we people recognize the beatiful surrounding that surrounds us. We also need light specially at night time, coz without light our world turns to be darker than ever. And mostly, we can't see without light. Light also give energy for us human and plants which we intend to use.
...hAiL!!, +mp678!!!.,
Yes, light is very important because of the kight, we can see our surroundings and also the image of the human. Light is very useful also in plants because without light, i think the plants can't produce their own food. We know that light came from the sun and without light, the earth will be in eternal darkness.
THE IMPORTANCE OF LIGHT
Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
For diurnal species (species that are active during the day), light is important for many reasons. Obviously, it is required for vision, and most birds have highly developed sight. For many species of animals, full-spectrum light is required for the conversion of cholesterol to vitamin D. Light and its changing cycles -- photoperiodicity is used by animals to synchronize their biological clocks. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals.
Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom. The extremely large eye leaves little room in the head for anything else. For example. an ostrich eye is 2 inches in diameter, an owl eye is one-third the entire head weight, and the buzzard eye has four times the visual acuity (sharpness) of a human eye.
Photoperiodicity has long been studied in birds as a means of inducing reproduction. Day length is detected by the pineal gland. The adrenal gland is located in the brain between the cerebella hemispheres and the cerebellum. It has numerous functions, one of which is photoreceptor and regulator of circadian rhythms. Some photoreceptors are located deep within the brain and are not dependent upon the eyes for photoreception. The hormones of the pineal gland (melatonin primarily) affect sleep, behavior and brain electrical activity. There is also evidence that melatonin influences reproductive hormonal cycles by affecting the pituitary gland. This has been very important in inducing poultry to lay eggs and to maximize egg production.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
Numerous breeders of exotic birds have used changing the day length in an attempt to manipulate breeding. however, few controlled studies have been conducted to assess its effects. Work at the department of avian sciences at the University of California at Davis and elsewhere demonstrated that long day lengths stimulate reproductive activity in cockatiels and blossom-headed parakeets. In general. birds must be exposed to short day lengths (10 hours of light, 14 hours of dark). before they can respond to long day lengths. The length of the photoperiod that may be stimulatory can only be determined experimentally for each species, but it may range from 13 to 17 hours. Ideally, it would increase gradually. Many birds will become unresponsive to this stimulus after prolonged! light stimulation. Work at UC Davis showed that cockatiels became resistant after two clutches. For pet birds, the sometimes prolonged or erratic photoperiods that they are exposed to in the home may affect them behaviorally. A bird exhibiting signs of sexual over stimulation or frustration (such as plucking) may respond to a shortened day length.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass.
Vitamin D can be toxic, so be careful not to over supplement. Birds housed outdoors do not need supplemental vitamin D. Special Effects Light affects the health and well being of people and animals in numerous ways. Dr. John Ott did some of the pioneering studies in the 1960s and 1970s. He conducted numerous studies on the effects of light on plants and animals. He utilized time-lapse photography to demonstrate plant growth and the effects of limiting the photo spectrum. Working with fluorescent lights, such as cool white, daylight white. and warm white bulbs that were limited in spectrum, some plants would not flower properly. By using light filters to further limit the light spectrum he could produce signs suggestive of viral disease in plants. He conducted similar studies in mice and found that deprivation of part of the light spectrum could produce loss of fur, skin disease, curling and loss of the tail, and inflammation of the heart muscle (myocarditis). It also affected the behavior of the mice, making some aggressive and agitated. In studies of children in school where curtains were closed and limited spectrum fluorescent lights were used, children were hyperactive and inattentive. This behavior was corrected when the lights were changed and the curtains were opened. He also equated malillumination with malnutrition.
A recent Wall Street Journal report showed how light is being used to enhance human well being. Prior to the invention of the electric light in 1879, buildings were designed with an emphasis on placement of windows to enhance natural lighting. As architects relied more on electric lighting, natural lighting of buildings was reduced. The need for energy efficiency has again affected how we design our indoor spaces for light. Recently, European countries have begun to require that a percentage of a building's light come from outdoors -- 37 percent in the Netherlands, for example.
According to a report by the Rocky Mountain Institute in Snowmass, Colorado, increasing daylight results in fewer days lost to absenteeism and fewer errors and defects. The report, "Greening the Building and the Bottom Line", cites improved heating and cooling in eight commercial buildings thanks to natural light. Installation of special skylights and-tall windows improved lighting and cut lighting costs by up to 75 percent. An unexpected effect was a 15-percent drop in employee absenteeism, as well as increased productivity and sales.
People living in northern cities that are overcast for long periods of time and receive little sunshine typically report depression. Birds housed continually indoors may also suffer from depression. Taking your wing-clipped bird outdoors for a bath in the sun is great for its plumage and its spirits. If you have the opportunity to see the plumage quality of birds housed outdoors that has access to rain and sunlight, you will be a believer.
Try to place your bird near a sunny window, but make sure it can move out of direct sunlight when it wants. A useful substitute may be a full-spectrum fluorescent bulb with the fixture close enough to the bird to provide the UV spectrum. Ideally, the bulb should be within a foot or two of the bird to provide benefits.
Remember that the capability of the bulb to produce UV does not last for the life of the bulb. The bulb can still be used for general lighting purposes after it is no longer producing full-spectrum light. Certainly, we must not forget the potential hazard of excessive UV exposure, such a skin cancer and eye disease.®
Bird Talk Magazine by Susan L. Clubb, D.V.M., DIP., AVBP - March 1996
--------------------------------------------------------------------------------
All animals are dependent on light to some extent, but birds are particularly sensitive to it. Birds deprived of sunlight may develop a variety of problems, including poor nutrient absorption, vitamin D deficiency, feather plucking, and disruption of mating and breeding patterns.
Many bird owners place their pet's cage near a window or other light source, but that may not be enough to cure the problem, since glass can act as a filter, reflecting instead of transmitting certain portions of the spectrum.
Dr. John Ott's research into the light needs of people, plants and animals led to the invention of full-spectrum lighting, a term coined by Ott. Full-spectrum lighting recreates the light-environment birds and others have in the wild. The poultry industry has already discovered that the benefits of providing full-spectrum lighting include increased egg production, larger eggs with stronger shells, and healthier birds. Couldn't your bird benefit?
Pet bird keepers know that their companions need fresh air, proper foods and a constant supply of clean water in order to survive and thrive. But not everyone knows that birds need light, as well, for optimum health. Larges suppliers of Proper Lighting for birds are listed here:
Duro-Test Lighting Corp
Nine Law Drive
Fairfield, NJ 07004
(973)808-1800;
Fax (973)808-6633
Environmental Lighting Concepts Inc.
(OTT-LITE Technology)
3923 Cocomut Palm Drive,
Tampa, FL 33619
(800)842-8848;
Fax: (813)626-8790
Verilux
P.O. Box 2937
Stanford, CT 06906
(203)921-2430;
Fax: (203)921-242 7
Reprinted by Pretty Birds from Pet Business Inc.
--------------------------------------------------------------------------------
Warning: Lighting: You may not be getting what you think you're buying.
Any incandescent bulb is fine for heat (for night time, you want dark light, such as the Nocturnal Light by Energy Savers Unlimited or a ceramic heating element). The technology (tungsten filament vs. the gases and coatings used in fluorescents) doesn't produce UVB, and only marginal UVA (which are the wavelengths in between UVB and visible light).
"Full spectrum" is a term used rather loosely. It can mean "produces UVB, UVA, visible light and infrared [the wavelengths longer than those in the spectrum we can see {visible light}] but the reality is that manufacturers of incandescents are calling their bulbs "full spectrum" to lull people into thinking they are getting UVB (and thus buying their product) when they are not. Incandescents are fine to use alone for room lighting, but birds require UVB. Also, birds from more northerly climates or colder temperature climates that do well with minimal UVB obtained from occasional exposure to natural sun thru windows, must have lighting used in conjunction with a UVB-producing fluorescents or lamps (not all fluorescents produce UVB or enough of it to do any good).
What's the difference between a WIDE Spectrum and a FULL Spectrum light?
Ahhhh....welcome to the Madison Avenue and the non-regulated pet product industry where accuracy never gets in the way of making product claims! Because there are no truth-in-advertising regulations covering pet products, manufactures can be as misleading as they like.
It used to be that 'full spectrum' lighting meant lights which produced both ultraviolet B, ultraviolet A and the full visible spectrum as well infrared heat. Once incandescent manufacturers figured out that people were being told to look for 'full spectrum' lighting, they started to market their wide spectrum (producing some, but not all of the visible wavelengths and no ultraviolet wavelengths) lights with 'full spectrum' in the ads and on packaging. Thus people are buying Chromalux, NeoWhite and "Full Spectrum" incandescent lights thought, incorrectly, that they are providing UVB, UVA and full visible wavelengths to their birds. In fact, incandescents are just producing, if they are putting out bright white light, only the visible spectrum; some which produce colored light, are not necessarily even producing the full visible spectrum, being corrected to increase or reduce certain parts of that spectrum.
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;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
Natural light is so important that we would fail to thrive without it. In fact, artists and those in the know spend thousands of dollars ensuring that they have natural light — and plenty of it — in their homes and workspaces. If you are tired, sluggish, depressed, and altogether unsatisfied with your home or your workspace, one of the first things to suspect is a lack of adequate lighting. Take a good look around your workspace or your living environment. Are there big windows in the rooms where you spend a large amount of time? Are there adequate numbers of windows which give natural light as well as fresh air? In the room where you sleep, is there a large window that provides natural light as well as fresh air in the morning? This is especially important, since you will have a hard time waking up in a room that is dark in the morning, and you will have a hard time getting good sleep in a room with small windows that provide poor ventilation.
Start becoming aware of the light in the rooms where you work and relax. If you are in a dingy, dark room, it will be very hard for you to be productive at work. It will also be difficult for you to feel alert and well. Similarly, it will be hard for you to relax and rest in a room with small windows.
Large windows that let in natural light make working or just relaxing far more enjoyable. Large windows let you look out at the beauty of nature and allow you to watch the world go by. Far from being distracting, they can allow you to have the lighting you need in order to do your work without ruining your eyes. Natural lighting can be one of the best light sources to work by. Large windows that let in lots of light will also allow you to achieve a better communication between exterior world and interior world. You feel more connected with your overall environment less isolated if you have adequate windows. Of course, natural light will also ensure that you get adequate of vitamin D, which is very important to your overall health. When you spend a lot of time in dark rooms, you look pasty and you don’t feel at your best. If you are busy and do not always get to spend plenty of time outdoors, you especially need to ensure that your windows let in as much natural sunlight as possible.
If your windows are small, dark, or don’t let in enough light, consider getting renovations. Although it may seem extreme, the cost, time, and effort of renovations when it comes to windows is well worth it. Not only can good windows save your eyesight, but they can also ensure that you are as receptive, happy, and healthy as possible. Look online for inexpensive windows solutions, and be sure to read all about all the window options available today. From vinyl windows to old-fashioned wooden frames, you’re sure to find a natural lighting solution that suits your style and your budget. While shopping, be sure to pick out some pretty blinds and curtains that will help you enjoy your new windows and your new outlook on life.
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
Natural light is so important that we would fail to thrive without it. In fact, artists and those in the know spend thousands of dollars ensuring that they have natural light — and plenty of it — in their homes and workspaces. If you are tired, sluggish, depressed, and altogether unsatisfied with your home or your workspace, one of the first things to suspect is a lack of adequate lighting. Take a good look around your workspace or your living environment. Are there big windows in the rooms where you spend a large amount of time? Are there adequate numbers of windows which give natural light as well as fresh air? In the room where you sleep, is there a large window that provides natural light as well as fresh air in the morning? This is especially important, since you will have a hard time waking up in a room that is dark in the morning, and you will have a hard time getting good sleep in a room with small windows that provide poor ventilation.
Start becoming aware of the light in the rooms where you work and relax. If you are in a dingy, dark room, it will be very hard for you to be productive at work. It will also be difficult for you to feel alert and well. Similarly, it will be hard for you to relax and rest in a room with small windows.
Large windows that let in natural light make working or just relaxing far more enjoyable. Large windows let you look out at the beauty of nature and allow you to watch the world go by. Far from being distracting, they can allow you to have the lighting you need in order to do your work without ruining your eyes. Natural lighting can be one of the best light sources to work by. Large windows that let in lots of light will also allow you to achieve a better communication between exterior world and interior world. You feel more connected with your overall environment less isolated if you have adequate windows. Of course, natural light will also ensure that you get adequate of vitamin D, which is very important to your overall health. When you spend a lot of time in dark rooms, you look pasty and you don’t feel at your best. If you are busy and do not always get to spend plenty of time outdoors, you especially need to ensure that your windows let in as much natural sunlight as possible.
If your windows are small, dark, or don’t let in enough light, consider getting renovations. Although it may seem extreme, the cost, time, and effort of renovations when it comes to windows is well worth it. Not only can good windows save your eyesight, but they can also ensure that you are as receptive, happy, and healthy as possible. Look online for inexpensive windows solutions, and be sure to read all about all the window options available today. From vinyl windows to old-fashioned wooden frames, you’re sure to find a natural lighting solution that suits your style and your budget. While shopping, be sure to pick out some pretty blinds and curtains that will help you enjoy your new windows and your new outlook on life.
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
Natural light is so important that we would fail to thrive without it. In fact, artists and those in the know spend thousands of dollars ensuring that they have natural light — and plenty of it — in their homes and workspaces. If you are tired, sluggish, depressed, and altogether unsatisfied with your home or your workspace, one of the first things to suspect is a lack of adequate lighting. Take a good look around your workspace or your living environment. Are there big windows in the rooms where you spend a large amount of time? Are there adequate numbers of windows which give natural light as well as fresh air? In the room where you sleep, is there a large window that provides natural light as well as fresh air in the morning? This is especially important, since you will have a hard time waking up in a room that is dark in the morning, and you will have a hard time getting good sleep in a room with small windows that provide poor ventilation.
Start becoming aware of the light in the rooms where you work and relax. If you are in a dingy, dark room, it will be very hard for you to be productive at work. It will also be difficult for you to feel alert and well. Similarly, it will be hard for you to relax and rest in a room with small windows.
Large windows that let in natural light make working or just relaxing far more enjoyable. Large windows let you look out at the beauty of nature and allow you to watch the world go by. Far from being distracting, they can allow you to have the lighting you need in order to do your work without ruining your eyes. Natural lighting can be one of the best light sources to work by. Large windows that let in lots of light will also allow you to achieve a better communication between exterior world and interior world. You feel more connected with your overall environment less isolated if you have adequate windows. Of course, natural light will also ensure that you get adequate of vitamin D, which is very important to your overall health. When you spend a lot of time in dark rooms, you look pasty and you don’t feel at your best. If you are busy and do not always get to spend plenty of time outdoors, you especially need to ensure that your windows let in as much natural sunlight as possible.
If your windows are small, dark, or don’t let in enough light, consider getting renovations. Although it may seem extreme, the cost, time, and effort of renovations when it comes to windows is well worth it. Not only can good windows save your eyesight, but they can also ensure that you are as receptive, happy, and healthy as possible. Look online for inexpensive windows solutions, and be sure to read all about all the window options available today. From vinyl windows to old-fashioned wooden frames, you’re sure to find a natural lighting solution that suits your style and your budget. While shopping, be sure to pick out some pretty blinds and curtains that will help you enjoy your new windows and your new outlook on life.
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
Light is essential to maintaining normal, healthy physiology. Exposure to sunrise is key to synchronizing our internal body cycles to the external world (so we sleep when it is dark and are alert during the day).
Modern industrial society began to tamper with this system, though. The loss of natural light - in dark apartments, in the workplace, on shift work, etc. - creates a state of light deprivation, making us vulnerable to depressed mood, sleep problems, fatigue, ability to concentrate, and more. Nature, too, posed a new problem when humans began to migrate north, where winter nights are long and dark.
Light levels as measured in lux vary greatly between indoor and outdoor lighting. You can see from the chart below how easy it is to become light deprived in our modern, indoor society.
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
Light is essential to maintaining normal, healthy physiology. Exposure to sunrise is key to synchronizing our internal body cycles to the external world (so we sleep when it is dark and are alert during the day).
Modern industrial society began to tamper with this system, though. The loss of natural light - in dark apartments, in the workplace, on shift work, etc. - creates a state of light deprivation, making us vulnerable to depressed mood, sleep problems, fatigue, ability to concentrate, and more. Nature, too, posed a new problem when humans began to migrate north, where winter nights are long and dark.
Light levels as measured in lux vary greatly between indoor and outdoor lighting. You can see from the chart below how easy it is to become light deprived in our modern, indoor society.
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
Light is essential to maintaining normal, healthy physiology. Exposure to sunrise is key to synchronizing our internal body cycles to the external world (so we sleep when it is dark and are alert during the day).
Modern industrial society began to tamper with this system, though. The loss of natural light - in dark apartments, in the workplace, on shift work, etc. - creates a state of light deprivation, making us vulnerable to depressed mood, sleep problems, fatigue, ability to concentrate, and more. Nature, too, posed a new problem when humans began to migrate north, where winter nights are long and dark.
Light levels as measured in lux vary greatly between indoor and outdoor lighting. You can see from the chart below how easy it is to become light deprived in our modern, indoor society.
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
The bottom line is: without light, there would be no sight. The visual ability of humans and other animals is the result of the complex interaction of light, eyes and brain. We are able to see because light from an object can move through space and reach our eyes. Once light reaches our eyes, signals are sent to our brain, and our brain deciphers the information in order to detect the appearance, location and movement of the objects we are sighting at. The whole process, as complex as it is, would not be possible if it were not for the presence of light. Without light, there would be no sight.
If you were to turn off the room lights for a moment and then cover all the windows with black construction paper to prevent any entry of light into the room, then you would notice that nothing in the room would be visible. There would be objects present that were capable of being seen. There would be eyes present which would be capable of detecting light from those objects. There would be a brain present which would be capable of deciphering the information sent to it. But there would be no light! The room and everything in it would look black. The appearance of black is merely a sign of the absence of light. When a room full of objects (or a table, a shirt or a sky) looks black, then the objects are not generating nor reflecting light to your eyes. And without light, there would be no sight.
The objects which we see can be placed into one of two categories: luminous objects and illuminated objects. Luminous objects are objects which generate their own light. Illuminated objects are objects which are capable of reflecting light to our eyes. The sun is an example of a luminous object, while the moon is an illuminated object. During the day, the sun generates sufficient light to illuminate objects on Earth. The blue skies, the white clouds, the green grass, the colored leaves of fall, the neighbor's house, and the car approaching the intersection are all seen as a result of light from the sun (the luminous object) reflecting off the illuminated objects and traveling to our eyes. Without the light from the luminous objects, these illuminated objects would not be seen. During the evening when the Earth has rotated to a position where the light from the sun can no longer reach our part of the Earth (due to its inability to bend around the spherical shape of the Earth), objects on Earth appear black (or at least so dark that we could say they are nearly black). In the absence of a porch light or a street light, the neighbor's house can no longer be seen; the grass is no longer green, but rather black; the leaves on the trees are dark; and were it not for the headlights of the car, it would not be seen approaching the intersection. Without luminous objects generating light which propagates through space to illuminate non-luminous objects, those non-luminous objects cannot bee seen. Without light, there would be no sight.
A common Physics demonstration involves the directing of a laser beam across the room. With the room lights off, the laser is turned on and its beam is directed towards a plane mirror. The presence of the light beam cannot be detected as it travels towards the mirror. Furthermore, the light beam cannot be detected after reflecting off the mirror and traveling through the air towards a wall in the room. The only locations where the presence of the light beam can be detected are at the location where the light beam strikes the mirror and at the location where the light beam strikes a wall. At these two locations, a portion of the light in the beam is reflecting off the objects (the mirror and the wall) and traveling towards the students' eyes. And since the detection of objects is dependent upon light traveling from that object to the eye, these are the only two locations where one can detect the light beam. But in between the laser and the mirror, the light beam cannot be detected. There is nothing present in the region between the laser and the mirror which is capable of reflecting the light of the beam to students' eyes.
;quail assignment 1.,
-> Is LIGHT valuable?
->answer:
The bottom line is: without light, there would be no sight. The visual ability of humans and other animals is the result of the complex interaction of light, eyes and brain. We are able to see because light from an object can move through space and reach our eyes. Once light reaches our eyes, signals are sent to our brain, and our brain deciphers the information in order to detect the appearance, location and movement of the objects we are sighting at. The whole process, as complex as it is, would not be possible if it were not for the presence of light. Without light, there would be no sight.
If you were to turn off the room lights for a moment and then cover all the windows with black construction paper to prevent any entry of light into the room, then you would notice that nothing in the room would be visible. There would be objects present that were capable of being seen. There would be eyes present which would be capable of detecting light from those objects. There would be a brain present which would be capable of deciphering the information sent to it. But there would be no light! The room and everything in it would look black. The appearance of black is merely a sign of the absence of light. When a room full of objects (or a table, a shirt or a sky) looks black, then the objects are not generating nor reflecting light to your eyes. And without light, there would be no sight.
The objects which we see can be placed into one of two categories: luminous objects and illuminated objects. Luminous objects are objects which generate their own light. Illuminated objects are objects which are capable of reflecting light to our eyes. The sun is an example of a luminous object, while the moon is an illuminated object. During the day, the sun generates sufficient light to illuminate objects on Earth. The blue skies, the white clouds, the green grass, the colored leaves of fall, the neighbor's house, and the car approaching the intersection are all seen as a result of light from the sun (the luminous object) reflecting off the illuminated objects and traveling to our eyes. Without the light from the luminous objects, these illuminated objects would not be seen. During the evening when the Earth has rotated to a position where the light from the sun can no longer reach our part of the Earth (due to its inability to bend around the spherical shape of the Earth), objects on Earth appear black (or at least so dark that we could say they are nearly black). In the absence of a porch light or a street light, the neighbor's house can no longer be seen; the grass is no longer green, but rather black; the leaves on the trees are dark; and were it not for the headlights of the car, it would not be seen approaching the intersection. Without luminous objects generating light which propagates through space to illuminate non-luminous objects, those non-luminous objects cannot bee seen. Without light, there would be no sight.
A common Physics demonstration involves the directing of a laser beam across the room. With the room lights off, the laser is turned on and its beam is directed towards a plane mirror. The presence of the light beam cannot be detected as it travels towards the mirror. Furthermore, the light beam cannot be detected after reflecting off the mirror and traveling through the air towards a wall in the room. The only locations where the presence of the light beam can be detected are at the location where the light beam strikes the mirror and at the location where the light beam strikes a wall. At these two locations, a portion of the light in the beam is reflecting off the objects (the mirror and the wall) and traveling towards the students' eyes. And since the detection of objects is dependent upon light traveling from that object to the eye, these are the only two locations where one can detect the light beam. But in between the laser and the mirror, the light beam cannot be detected. There is nothing present in the region between the laser and the mirror which is capable of reflecting the light of the beam to students' eyes.
Light, form of energy visible to the human eye that is radiated by moving charged particles. Light from the Sun provides the energy needed for plant growth. Plants convert the energy in sunlight into storable chemical form through a process called photosynthesis. Petroleum, coal, and natural gas are the remains of plants that lived millions of years ago, and the energy these fuels release when they burn is the chemical energy converted from sunlight. When animals digest the plants and animals they eat, they also release energy stored by photosynthesis.
Scientists have learned through experimentation that light behaves like a particle at times and like a wave at other times. The particle-like features are called photons. Photons are different from particles of matter in that they have no mass and always move at the constant speed of about 300,000 km/sec (186,000 mi/sec) when they are in a vacuum. When light diffracts, or bends slightly as it passes around a corner, it shows wavelike behavior. The waves associated with light are called electromagnetic waves because they consist of changing electric and magneticfields.
Sources of light differ in how they provide energy to the charged particles, such as electrons, whose motion creates the light. If the energy comes from heat, then the source is called incandescent. If the energy comes from another source, such as chemical or electric energy, the source is called luminescent.
The waves that accompany light are made up of oscillating, or vibrating, electric and magnetic fields, which are force fields that surround charged particles and influence other charged particles in their vicinity. These electric and magnetic fields change strength and direction at right angles, or perpendicularly, to each other in a plane (vertically and horizontally for instance). The electromagnetic wave formed by these fields travels in a direction perpendicular to the field’s strength (coming out of the plane). The relationship between the fields and the wave formed can be understood by imagining a wave in a taut rope. Grasping the rope and moving it up and down simulates the action of a moving charge upon the electric field. It creates a wave that travels along the rope in a direction that is perpendicular to the initial up and down movement.
Because electromagnetic waves are transverse—that is, the vibration that creates them is perpendicular to the direction in which they travel, they are similar to waves on a rope or waves traveling on the surface of water. Unlike these waves, however, which require a rope or water, light does not need a medium, or substance, through which to travel. Light from the Sun and distant stars reaches Earth by traveling through the vacuum of space.
The waves associated with natural sources of light are irregular, like the water waves in a busy harbor. Scientists think of such waves as being made up of many smooth waves, where the motion is regular and the wave stretches out indefinitely with regularly spaced peaks and valleys. Such regular waves are called monochromatic because they correspond to a single color of light.
thatz all!!!tnx maam,.,bye2x.
GOD BLESS!!!
Light may be the cure for what’s ailing your bird. SUNLIGHT POWERS ALL LIFE ON earth, either directly or indirectly. Plants obviously must have sunlight or full-spectrum artificial light to manufacture their food by photosynthesis. Plants, in turn, pass on their energy to the animals that consume them. Light is also essential for the survival of most animal species. Animals that have evolved in total darkness (cave dwellers or deep-sea life. for example) do not require light, but nocturnal animals require low-level light.
For diurnal species (species that are active during the day), light is important for many reasons. Obviously, it is required for vision, and most birds have highly developed sight. For many species of animals, full-spectrum light is required for the conversion of cholesterol to vitamin D. Light and its changing cycles -- photoperiodicity is used by animals to synchronize their biological clocks. Full-spectrum light may be needed for the maintenance of health in ways still unknown, add, finally, light is important for the psychological well being of animals.
Avian species, including nocturnal birds, are highly dependent upon sight for survival. The avian eye displays the basic pattern of a vertebrate's eyes, but it incorporates many adaptations that have improved visual abilities. The avian eve is considered to be the finest ocular organ in the animal kingdom. The extremely large eye leaves little room in the head for anything else. For example. an ostrich eye is 2 inches in diameter, an owl eye is one-third the entire head weight, and the buzzard eye has four times the visual acuity (sharpness) of a human eye.
Photoperiodicity has long been studied in birds as a means of inducing reproduction. Day length is detected by the pineal gland. The adrenal gland is located in the brain between the cerebella hemispheres and the cerebellum. It has numerous functions, one of which is photoreceptor and regulator of circadian rhythms. Some photoreceptors are located deep within the brain and are not dependent upon the eyes for photoreception. The hormones of the pineal gland (melatonin primarily) affect sleep, behavior and brain electrical activity. There is also evidence that melatonin influences reproductive hormonal cycles by affecting the pituitary gland. This has been very important in inducing poultry to lay eggs and to maximize egg production.
Obviously, light cycling is most important in birds from northern or temperate climates where changes in the light cycle are the greatest. We often assume that birds living on the equator are not affected by day length, however, the slightly elliptical shape of the earth results in about a 20-minute change in light cycles that can affect reproductive cycles of equatorial birds.
Numerous breeders of exotic birds have used changing the day length in an attempt to manipulate breeding. however, few controlled studies have been conducted to assess its effects. Work at the department of avian sciences at the University of California at Davis and elsewhere demonstrated that long day lengths stimulate reproductive activity in cockatiels and blossom-headed parakeets. In general. birds must be exposed to short day lengths (10 hours of light, 14 hours of dark). before they can respond to long day lengths. The length of the photoperiod that may be stimulatory can only be determined experimentally for each species, but it may range from 13 to 17 hours. Ideally, it would increase gradually. Many birds will become unresponsive to this stimulus after prolonged! light stimulation. Work at UC Davis showed that cockatiels became resistant after two clutches. For pet birds, the sometimes prolonged or erratic photoperiods that they are exposed to in the home may affect them behaviorally. A bird exhibiting signs of sexual over stimulation or frustration (such as plucking) may respond to a shortened day length.
The effects of light on health may also be important in pet birds. Wild birds utilize sunlight for production of vitamin D3. Birds that are kept indoors and on a poor diet can develop a vitamin D deficiency. All seed diets are usually deficient in vitamin D and calcium. Vitamin D deficiency in growing birds results in rickets and bone fractures. A deficiency in adult birds can result in poor utilization of calcium and osteomalacia (loss of calcium from the bones), or hypocalcemia (low blood calcium). Birds that get no natural light should be supplemented with vitamin D3. The UV portion of sunlight that is necessary for vitamin D production will not pass through glass.
Vitamin D can be toxic, so be careful not to over supplement. Birds housed outdoors do not need supplemental vitamin D. Special Effects Light affects the health and well being of people and animals in numerous ways. Dr. John Ott did some of the pioneering studies in the 1960s and 1970s. He conducted numerous studies on the effects of light on plants and animals. He utilized time-lapse photography to demonstrate plant growth and the effects of limiting the photo spectrum. Working with fluorescent lights, such as cool white, daylight white. and warm white bulbs that were limited in spectrum, some plants would not flower properly. By using light filters to further limit the light spectrum he could produce signs suggestive of viral disease in plants. He conducted similar studies in mice and found that deprivation of part of the light spectrum could produce loss of fur, skin disease, curling and loss of the tail, and inflammation of the heart muscle (myocarditis). It also affected the behavior of the mice, making some aggressive and agitated. In studies of children in school where curtains were closed and limited spectrum fluorescent lights were used, children were hyperactive and inattentive. This behavior was corrected when the lights were changed and the curtains were opened. He also equated malillumination with malnutrition.
A recent Wall Street Journal report showed how light is being used to enhance human well being. Prior to the invention of the electric light in 1879, buildings were designed with an emphasis on placement of windows to enhance natural lighting. As architects relied more on electric lighting, natural lighting of buildings was reduced. The need for energy efficiency has again affected how we design our indoor spaces for light. Recently, European countries have begun to require that a percentage of a building's light come from outdoors -- 37 percent in the Netherlands, for example.
According to a report by the Rocky Mountain Institute in Snowmass, Colorado, increasing daylight results in fewer days lost to absenteeism and fewer errors and defects. The report, "Greening the Building and the Bottom Line", cites improved heating and cooling in eight commercial buildings thanks to natural light. Installation of special skylights and-tall windows improved lighting and cut lighting costs by up to 75 percent. An unexpected effect was a 15-percent drop in employee absenteeism, as well as increased productivity and sales.
People living in northern cities that are overcast for long periods of time and receive little sunshine typically report depression. Birds housed continually indoors may also suffer from depression. Taking your wing-clipped bird outdoors for a bath in the sun is great for its plumage and its spirits. If you have the opportunity to see the plumage quality of birds housed outdoors that has access to rain and sunlight, you will be a believer.
Try to place your bird near a sunny window, but make sure it can move out of direct sunlight when it wants. A useful substitute may be a full-spectrum fluorescent bulb with the fixture close enough to the bird to provide the UV spectrum. Ideally, the bulb should be within a foot or two of the bird to provide benefits.
Remember that the capability of the bulb to produce UV does not last for the life of the bulb. The bulb can still be used for general lighting purposes after it is no longer producing full-spectrum light. Certainly, we must not forget the potential hazard of excessive UV exposure, such a skin cancer and eye disease.®
Why does light matter?
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light
The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming
Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene lanterns in the developing world with solar powered lights is equivalent to removing one vehicle from the roads here in the US.
Battery Groundwater Contamination
The EPA notes that “The single largest source of mercury in garbage is household batteries, especially alkaline and button batteries. Mercury is a heavy metal with high toxicity. Long-term exposure can permanently damage the brain, kidneys, and fetuses. The major way people get exposed to mercury is by eating mercury-contaminated food, especially fish.” After kerosene and candles, the most prevalent source of lighting in the developing world is conventional flashlights. According to its web-site, the Energizer Corporation, manufactures six billion batteries annually. Consider the environmental and damage to humans when even a fraction of these batteries are sold in developing nations and improperly disposed of. We are committed to addressing this problem. Our products are powered by rechargeable batteries, which only need to be replaced every two to three years, and we are also working on a buy-back/exchange program.
Deforestation and Top Soil Erosion
The actual rate of deforestation for lighting is difficult to quantify due to the lack of specific reporting data. Anecdotal reporting and common sense indicate that wood fires in developing countries are kept going long after the meal preparation to provide residual lighting. The loss of underbrush contributes to top soil erosion, which negatively impacts farmers. We intend to alleviate these two problems by reducing the consumption of wood for lighting purposes.
Health and Safety Cancer
According to the World Bank, 1.6 million people die each year from indoor air pollution associated with the burning of wood, dung, agricultural residues, and coal. That is one person every twenty seconds. The World Bank also notes that 780 million people in the developing world, mostly women and children, are exposed to kerosene lantern fumes equivalent to two packs of cigarettes a day. More than two-thirds of lung cancer victims in the developing world are female, as women are the primary homemakers. Help us change these alarming statistics by giving them the gift of clean, solar light!
Accidental Fires
Hundreds of thousands of people are injured or killed each year and their homes destroyed by accidental fires caused by the widespread use of kerosene lanterns. Help us reduce these preventable tragedies by replacing their kerosene lanterns with safe, solar light.
Malaria
Mosquitoes are attracted to kerosene light, but they are not naturally attracted to light given off by white light emitting diodes (LEDs). The reason for this is that mosquitoes have receptors which detect carbon dioxide, and kerosene lanterns emit volumes of carbon dioxide whereas LEDs do not. This suggests that people using our LED powered lights may lower their risk of contracting malaria. This is an exciting idea, and we have contacted the Center for Disease Control about conducting follow-on studies once our lights become more widely distributed.
Poverty and Economic Costs
A study conducted by the joint UN Development Program/World Bank Energy Sector Management Assistance Program (ESMAP) found that rural households spending as much as US$10 per month on lighting from candles, kerosene, and dry cell batteries. In some cases, this is up to thirty percent of a developing world family’s income. BoGo Light can be an engine for change. Giving needy families free lights allows them to redirect their limited resources into other areas besides lighting – education, health, etc. Imagine the profound changes this could bring about! And the best part is that light empowers them without creating dependency.
Women Empowerment and Family Security
Night time is a dangerous time for many people in developing countries, especially for refugees. It is expensive to import diesel fuel for generators and kerosene for lanterns into refugee camps; therefore, lighting is regulated and often limited both in duration and areas illuminated. Without portable lights at night, refugees must either travel at their own risk or remain homebound. Even remaining homebound, women and children are too often the victims of armed attacks and crimes in the dangerous dark. The portable, reliable BoGo Light can help liberate these people by giving them freedom of movement and freedom from fear. The freedom to move safely at night will greatly improve their quality of life, and parents equipped with lights can better observe and protect their children at night.
How is the BoGo Light distributed?
The donated lights are distributed to needy individuals and families by organizations that are established and working in the developing world. These organizations include Feed The Children, Samaritan's Purse, UNHCR, and Invisible Children, as well as many other international assistance groups. Our lights have also been bulk purchased by multinational corporations such as Exxon Mobil and Perenco, as part of their community assistance programs.
Why does light matter?
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light
The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming
Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene lanterns in the developing world with solar powered lights is equivalent to removing one vehicle from the roads here in the US.
Battery Groundwater Contamination
The EPA notes that “The single largest source of mercury in garbage is household batteries, especially alkaline and button batteries. Mercury is a heavy metal with high toxicity. Long-term exposure can permanently damage the brain, kidneys, and fetuses. The major way people get exposed to mercury is by eating mercury-contaminated food, especially fish.” After kerosene and candles, the most prevalent source of lighting in the developing world is conventional flashlights. According to its web-site, the Energizer Corporation, manufactures six billion batteries annually. Consider the environmental and damage to humans when even a fraction of these batteries are sold in developing nations and improperly disposed of. We are committed to addressing this problem. Our products are powered by rechargeable batteries, which only need to be replaced every two to three years, and we are also working on a buy-back/exchange program.
Deforestation and Top Soil Erosion
The actual rate of deforestation for lighting is difficult to quantify due to the lack of specific reporting data. Anecdotal reporting and common sense indicate that wood fires in developing countries are kept going long after the meal preparation to provide residual lighting. The loss of underbrush contributes to top soil erosion, which negatively impacts farmers. We intend to alleviate these two problems by reducing the consumption of wood for lighting purposes.
Health and Safety Cancer
According to the World Bank, 1.6 million people die each year from indoor air pollution associated with the burning of wood, dung, agricultural residues, and coal. That is one person every twenty seconds. The World Bank also notes that 780 million people in the developing world, mostly women and children, are exposed to kerosene lantern fumes equivalent to two packs of cigarettes a day. More than two-thirds of lung cancer victims in the developing world are female, as women are the primary homemakers. Help us change these alarming statistics by giving them the gift of clean, solar light!
Accidental Fires
Hundreds of thousands of people are injured or killed each year and their homes destroyed by accidental fires caused by the widespread use of kerosene lanterns. Help us reduce these preventable tragedies by replacing their kerosene lanterns with safe, solar light.
Malaria
Mosquitoes are attracted to kerosene light, but they are not naturally attracted to light given off by white light emitting diodes (LEDs). The reason for this is that mosquitoes have receptors which detect carbon dioxide, and kerosene lanterns emit volumes of carbon dioxide whereas LEDs do not. This suggests that people using our LED powered lights may lower their risk of contracting malaria. This is an exciting idea, and we have contacted the Center for Disease Control about conducting follow-on studies once our lights become more widely distributed.
Poverty and Economic Costs
A study conducted by the joint UN Development Program/World Bank Energy Sector Management Assistance Program (ESMAP) found that rural households spending as much as US$10 per month on lighting from candles, kerosene, and dry cell batteries. In some cases, this is up to thirty percent of a developing world family’s income. BoGo Light can be an engine for change. Giving needy families free lights allows them to redirect their limited resources into other areas besides lighting – education, health, etc. Imagine the profound changes this could bring about! And the best part is that light empowers them without creating dependency.
Women Empowerment and Family Security
Night time is a dangerous time for many people in developing countries, especially for refugees. It is expensive to import diesel fuel for generators and kerosene for lanterns into refugee camps; therefore, lighting is regulated and often limited both in duration and areas illuminated. Without portable lights at night, refugees must either travel at their own risk or remain homebound. Even remaining homebound, women and children are too often the victims of armed attacks and crimes in the dangerous dark. The portable, reliable BoGo Light can help liberate these people by giving them freedom of movement and freedom from fear. The freedom to move safely at night will greatly improve their quality of life, and parents equipped with lights can better observe and protect their children at night.
How is the BoGo Light distributed?
The donated lights are distributed to needy individuals and families by organizations that are established and working in the developing world. These organizations include Feed The Children, Samaritan's Purse, UNHCR, and Invisible Children, as well as many other international assistance groups. Our lights have also been bulk purchased by multinational corporations such as Exxon Mobil and Perenco, as part of their community assistance programs.
Light is valuable because,light is a wonderful subject for school study partly because you can teach some facet of it at every grade level.Light is a complex phenomenon that is classically explained with a simple model based on rays and wavefronts. The Molecular Expressions Microscopy Primer explores many of the aspects of visible light starting with an introduction to electromagnetic radiation.A wide variety of sources are responsible for emission of electromagnetic radiation, and are generally categorized according to the specific spectrum of wavelengths generated by the source. Relatively long radio waves are produced by electrical current flowing through huge broadcast antennas, while much shorter visible light waves are produced by the energy state fluctuations of negatively charged electrons within atoms. The shortest form of electromagnetic radiation, gamma waves, results from decay of nuclear components at the center of the atom. The visible light that humans are able to see is usually a mixture of wavelengths whose varying composition is a function of the light source.
A majority of the common natural and artificial light sources emit a broad range of wavelengths that cover the entire visible light spectrum, with some extending into the ultraviolet and infrared regions as well. For simple lighting applications, such as interior room lights, flashlights, spot and automobile headlights, and a host of other consumer, business, and technical applications, the wide wavelength spectrum is acceptable and quite useful. However, in many cases it is desirable to narrow the wavelength range of light for specific applications that require a selected region of color or frequency. This task can be easily accomplished through the use of specialized filters that transmit some wavelengths and selectively absorb, reflect, refract, or diffract unwanted wavelengths.
Mankind has always been dependent upon energy from the sun's light both directly - for warmth, to dry clothing, to cook, and indirectly to provide food, water, and air. Our awareness of the value of the sun's rays revolves around the manner in which we benefit from the energy, but there are far more fundamental implications from the relationship between light and energy. Whether or not mankind devises ingenius mechanisms to harness the sun's energy, our planet and the changing environment contained within is naturally driven by the energy of sunlight.
For me,light is valuable because it helps us in our daily lives. Light, or visible light, is electromagnetic radiation of a wavelength that is visible to the human eye (about 400–700 nm). In a scientific context, the word light is sometimes used to refer to the entire electromagnetic spectrum. Moreover, in optics, the term "visible light" refers to electromagnetic radiation with wavelengths of ~300 nm (near UV) through ~1400 nm (near infrared). [1] Light is composed of elementary particles called photons.
During nighttime,it help us to do our works by the use of lamps that gives light to us.And light,also helped plants to have energy,in order the plants to live.Light has many uses that has a big contribution to us.So,we should give impotance to the
light.
........That`s all i can say,and thank you for the question!love u mwaaaaaaaaaaaaaahhhhhhhhh.......... Benzone Ali,crazy,sexy and waffa!hehehehehehehehehe...........
For me light is valuable because we see things every day, from the moment we get up in the morning until we go to sleep at night. We look at everything around us using light. We appreciate kids' crayon drawings, fine oil paintings, swirling computer graphics, gorgeous sunsets, a blue sky, shooting stars and rainbows. We rely on mirrors to make ourselves presentable, and sparkling gemstones to show affection. But did you ever stop to think that when we see any of these things, we are not directly connected to it? We are, in fact, seeing light -- light that somehow left objects far or near and reached our eyes. Light is all our eyes can really see. A light wave consists of energy in the form of electric and magnetic fields. The fields vibrate at right angles to the direction of movement of the wave, and at right angles to each other. Because light has both electric and magnetic fields, it is also referred to as electromagnetic radiation.The light fixtures and related equipment are some of the more expensive pieces of equipment both at initial setup up as well as in their contribution to daily operating costs. In addition to being necessary for the photosynthetic organisms we keep in our aquariums, light also provides the visual element of color. From talking to aquarists and perusing the various reef-related bulletin boards, it has been my experience that lighting and color are often a very misunderstood aspect of aquarium keeping. Given that lighting and color are important in the functional and aesthetic elements of reefkeeping, I feel it is important that hobbyists have a good understanding of light and color. The purpose of this series of articles is to provide beginning and intermediate reef aquarists with a comprehensive understanding of lighting concepts and terminology, and the ability to understand and comprehend lighting related discussions and data.Light is a form of energy, and to understand light we begin with the electromagnetic spectrum which is basically a grouping of all electromagnetic radiation arranged according to the amount of energy contained in the radiation. Visible light is a part of this electromagnetic spectrum that creates the sensation of light when it falls on the human eye.
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Natural light is so important that we would fail to thrive without it. In fact, artists and those in the know spend thousands of dollars ensuring that they have natural light — and plenty of it — in their homes and workspaces. If you are tired, sluggish, depressed, and altogether unsatisfied with your home or your workspace, one of the first things to suspect is a lack of adequate lighting. Take a good look around your workspace or your living environment. Are there big windows in the rooms where you spend a large amount of time? Are there adequate numbers of windows which give natural light as well as fresh air? In the room where you sleep, is there a large window that provides natural light as well as fresh air in the morning? This is especially important, since you will have a hard time waking up in a room that is dark in the morning, and you will have a hard time getting good sleep in a room with small windows that provide poor ventilation.
Start becoming aware of the light in the rooms where you work and relax. If you are in a dingy, dark room, it will be very hard for you to be productive at work. It will also be difficult for you to feel alert and well. Similarly, it will be hard for you to relax and rest in a room with small windows.
Large windows that let in natural light make working or just relaxing far more enjoyable. Large windows let you look out at the beauty of nature and allow you to watch the world go by. Far from being distracting, they can allow you to have the lighting you need in order to do your work without ruining your eyes. Natural lighting can be one of the best light sources to work by. Large windows that let in lots of light will also allow you to achieve a better communication between exterior world and interior world. You feel more connected with your overall environment less isolated if you have adequate windows. Of course, natural light will also ensure that you get adequate of vitamin D, which is very important to your overall health. When you spend a lot of time in dark rooms, you look pasty and you don’t feel at your best. If you are busy and do not always get to spend plenty of time outdoors, you especially need to ensure that your windows let in as much natural sunlight as possible.
If your windows are small, dark, or don’t let in enough light, consider getting renovations. Although it may seem extreme, the cost, time, and effort of renovations when it comes to windows is well worth it. Not only can good windows save your eyesight, but they can also ensure that you are as receptive, happy, and healthy as possible. Look online for inexpensive windows solutions, and be sure to read all about all the window options available today. From vinyl windows to old-fashioned wooden frames, you’re sure to find a natural lighting solution that suits your style and your budget. While shopping, be sure to pick out some pretty blinds and curtains that will help you enjoy your new windows and your new outlook on life.
LIGHT IS VERY VALUABLE SPECIALLY 2 HUMAN.WITHOUT LIGHT WE CANT SEE THINGS DURING NIGHT TIME.LIGHT HELPS US ENABLES 2 CAPTURE MOMENTS THROUGH PHOTOGRAPH.BY DA HELP OF DA LIGHT WE CAN SEE THINGS BETTER.......
LIGHT IS VERY VALUABLE SPECIALLY 2 HUMAN.WITHOUT LIGHT WE CANT SEE THINGS DURING NIGHT TIME.LIGHT HELPS US ENABLES 2 CAPTURE MOMENTS THROUGH PHOTOGRAPH.BY DA HELP OF DA LIGHT WE CAN SEE THINGS BETTER.......
;quail assignment 1 . ,
-> Is LIGHT valuable?
->answer:
Light,for me, is NOT VALUABLE or shall i say it's NOT IMPORTANT.It's not just IMPORTANT , it's VERY VERY IMPORTANT...
For LIGHT,together with heat, is the main source of ENERGY of our very own planet that's why we are here.If LIGHT is absent here on EARTH, i'm pretty sure that this planet of our's will be dim, gray, dead and there will be eternal darkness all over the place. LIGHT is a very important kind of ENERGY to our everyday living. Imagine, if there's no LIGHT in here, can we survive without it??? I guess we can't!! LIGHT gives LIFE! Would you agree with that?? Maybe you'll just say, "..OwZzZz??!!" or otherwise YES. LIGHT gives LIFE for it is the one, responsible or shall i say the main source of ENERGY which plants consume and then it will undergo into a so-called photosynthesis on which plants make their own food and these plants give off oxygen and we, humans, breathe in it and we also consume the plants,of course, by eating it so that we can survive, isn't it??... So in other words, LIGHT gives LIFE to the plants as well as to humans. For there will be no plants present if there's no LIGHT and in this case, we will die because of starving. So that's how LIGHT gives LIFE to us, humans. We also use LIGHT in everyday living.
In our homes, we use electrical energy and this particular energy provides LIGHT for us. Primitive Men also used LIGHT inorder to survive especially during the "ICE AGE", that is using flame that produces LIGHT by converting chemical energy to LIGHT. So see?? See the uncomparable importance of LIGHT. Even though we don't really care of conserving LIGHT, because it's a fact that Sun is the main source of it and we can never control it,hehe, so why conserve??! Let's just enjoy every single second of the Sun's LIGHT for there will be a day that our Sun will explode leaving behind our planet dark and dead. By the way. let's just bear in our mind that we're so lucky of having an energy that is responsible for the existence of various forms of life-the so-called "LIGHT"-...
THAT'S ALL AND 'TILL THEN...
AU REVOIR...MABUHAY=)
-END-
yes,light is very valuable and ofcourse it is very useful in our life.like the sunlight it served as the food of every plants in the planet.through sunlight we were able to generate electric power.We can also get strenght through sunlight.As present,laser beams has been used by many people to finish their work accurately especially in high-tech agency,private or government owned establishment.
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene lanterns in the developing world with solar powered lights is equivalent to removing one vehicle from the roads here in the US.
The EPA notes that “The single largest source of mercury in garbage is household batteries, especially alkaline and button batteries. Mercury is a heavy metal with high toxicity. Long-term exposure can permanently damage the brain, kidneys, and fetuses. The major way people get exposed to mercury is by eating mercury-contaminated food, especially fish.” After kerosene and candles, the most prevalent source of lighting in the developing world is conventional flashlights. According to its web-site, the Energizer Corporation, manufactures six billion batteries annually. Consider the environmental and damage to humans when even a fraction of these batteries are sold in developing nations and improperly disposed of. We are committed to addressing this problem. Our products are powered by rechargeable batteries, which only need to be replaced every two to three years, and we are also working on a buy-back/exchange program.
The actual rate of deforestation for lighting is difficult to quantify due to the lack of specific reporting data. Anecdotal reporting and common sense indicate that wood fires in developing countries are kept going long after the meal preparation to provide residual lighting. The loss of underbrush contributes to top soil erosion, which negatively impacts farmers. We intend to alleviate these two problems by reducing the consumption of wood for lighting purposes.
According to the World Bank, 1.6 million people die each year from indoor air pollution associated with the burning of wood, dung, agricultural residues, and coal. That is one person every twenty seconds. The World Bank also notes that 780 million people in the developing world, mostly women and children, are exposed to kerosene lantern fumes equivalent to two packs of cigarettes a day. More than two-thirds of lung cancer victims in the developing world are female, as women are the primary homemakers. Help us change these alarming statistics by giving them the gift of clean, solar light!
Hundreds of thousands of people are injured or killed each year and their homes destroyed by accidental fires caused by the widespread use of kerosene lanterns. Help us reduce these preventable tragedies by replacing their kerosene lanterns with safe, solar light.
Mosquitoes are attracted to kerosene light, but they are not naturally attracted to light given off by white light emitting diodes (LEDs). The reason for this is that mosquitoes have receptors which detect carbon dioxide, and kerosene lanterns emit volumes of carbon dioxide whereas LEDs do not. This suggests that people using our LED powered lights may lower their risk of contracting malaria. This is an exciting idea, and we have contacted the Center for Disease Control about conducting follow-on studies once our lights become more widely distributed.
A study conducted by the joint UN Development Program/World Bank Energy Sector Management Assistance Program (ESMAP) found that rural households spending as much as US$10 per month on lighting from candles, kerosene, and dry cell batteries. In some cases, this is up to thirty percent of a developing world family’s income. BoGo Light can be an engine for change. Giving needy families free lights allows them to redirect their limited resources into other areas besides lighting – education, health, etc. Imagine the profound changes this could bring about! And the best part is that light empowers them without creating dependency.
Night time is a dangerous time for many people in developing countries, especially for refugees. It is expensive to import diesel fuel for generators and kerosene for lanterns into refugee camps; therefore, lighting is regulated and often limited both in duration and areas illuminated. Without portable lights at night, refugees must either travel at their own risk or remain homebound. Even remaining homebound, women and children are too often the victims of armed attacks and crimes in the dangerous dark. The portable, reliable BoGo Light can help liberate these people by giving them freedom of movement and freedom from fear. The freedom to move safely at night will greatly improve their quality of life, and parents equipped with lights can better observe and protect their children at night.
The donated lights are distributed to needy individuals and families by organizations that are established and working in the developing world. These organizations include Feed The Children, Samaritan's Purse, UNHCR, and Invisible Children, as well as many other international assistance groups. Our lights have also been bulk purchased by multinational corporations such as Exxon Mobil and Perenco, as part of their community assistance programs.
dAts all..enx..
Dear Mesdame,
In my opinion light is very valuable,for without light we cannot live as simple as that.For light is the key for us to see,to see is for us to identify and to differentiate things from the other.To choose what are the things do we need and the things to be thrown out.
Light is the major factor why we have the sense of sight which gives us the ability to defend ourselves from various organisms.Without it,the world would not be like this.No buildings so high,no machines made that brought us a progessive civilation and no homes for us to live.For we cannot see,we cannot build.The only thing we could see is total darkness,listening to complete silence,for we cannot identify whom we are communicating at.Cannot even move for we are afraid that we might step to something that would risks our life.
Human beings and animals would be blind,alone,no helper for all things cannot see and cannot be seen.Light could be processed for our convenience.
I would not make my comment longer for I am almost out of words..hehehe..All things depend upon the light,all things live through of the light and all things improved because of the light.Light powers life on Earth and thats for sure.Thats all...Thank you.
Truly yours,
Kenmore B. Espinoza
now its purely my opinion ok?...
Light, or visible light, is electromagnetic radiation of a wavelength that is visible to the human eye (about 400–700 nm). In a scientific context, the word light is sometimes used to refer to the entire electromagnetic spectrum. Moreover, in optics, the term "visible light" refers to electromagnetic radiation with wavelengths of ~300 nm (near UV) through ~1400 nm (near infrared). [1] Light is composed of elementary particles called photons.
Three primary properties of light are:
Intensity;
Frequency or wavelength and;
Polarization.
Light can exhibit properties of both waves and particles. This property is referred to as wave–particle duality. The study of light, known as optics, is an important research area in modern physics.
Light is everywhere in our world. We need it to see: it carries information from the world to our eyes and brains. Seeing colors and shapes is second nature to us, yet light is a perplexing phenomenon when we study it more closely.
Here are some things to think about:
Our brains and eyes act together to make extraordinary things happen in perception. Movies are sequences of still pictures. Magazine pictures are arrays of dots.
Light acts like particles—little light bullets—that stream from the source. This explains how shadows work.
Light also acts like waves—ripples in space—instead of bullets. This explains how rainbows work. In fact, light is both. This "wave-particle duality" is one of the most confusing—and wonderful—principles of physics.
Scientists have spent lifetimes developing consistent physical, biological, chemical, and mathematical explanations for these principles. But we can start on the road to deeper understanding without all the equations by acting as scientists do: making observations, performing experiments, and testing our conjectures against what we see.
The activities in this lab are designed to give you ideas about light—and also about how you can use technology to explore light. Collectively, the activities are a sampler—rather than comprehensive demonstration—of these two topics:
Light in Color. Color is more than decoration, and perceiving color is tricky. Three activities help you see how colors interact and how we can use color as a scientific tool.
Laws of Light. Light behaves according to special rules; for example, it usually travels in a straight line and it bounces off mirrors at the same angle it hits them.
Light is everywhere in our world. We need it to see: it carries information from the world to our eyes and brains. Seeing colors and shapes is second nature to us, yet light is a perplexing phenomenon when we study it more closely.
Here are some things to think about:
Our brains and eyes act together to make extraordinary things happen in perception. Movies are sequences of still pictures. Magazine pictures are arrays of dots.
Light acts like particles—little light bullets—that stream from the source. This explains how shadows work.
Light also acts like waves—ripples in space—instead of bullets. This explains how rainbows work. In fact, light is both. This "wave-particle duality" is one of the most confusing—and wonderful—principles of physics.
Scientists have spent lifetimes developing consistent physical, biological, chemical, and mathematical explanations for these principles. But we can start on the road to deeper understanding without all the equations by acting as scientists do: making observations, performing experiments, and testing our conjectures against what we see.
The activities in this lab are designed to give you ideas about light—and also about how you can use technology to explore light. Collectively, the activities are a sampler—rather than comprehensive demonstration—of these two topics:
Light in Color. Color is more than decoration, and perceiving color is tricky. Three activities help you see how colors interact and how we can use color as a scientific tool.
Laws of Light. Light behaves according to special rules; for example, it usually travels in a straight line and it bounces off mirrors at the same angle it hits them.
Light, or visible light, is electromagnetic radiation of a wavelength that is visible to the human eye (about 400–700 nm). In a scientific context, the word light is sometimes used to refer to the entire electromagnetic spectrum. Moreover, in optics, the term "visible light" refers to electromagnetic radiation with wavelengths of ~300 nm (near UV) through ~1400 nm (near infrared). [1] Light is composed of elementary particles called photons
A beam of white light (entering upwards from the right) is dispersed into its constituent colors by its passage through a prism. The fainter beam of white light exiting to the upper right has been reflected (without dispersion) off the first surface of the prism.
The speed of light in a vacuum is exactly 299,792,458 m/s (about 186,282.397 miles per second). The speed of light depends upon the medium in which it is traveling, and the speed will be lower in a transparent medium. Although commonly called the "velocity of light", technically the word velocity is a vector quantity, having both magnitude and direction. Speed refers only to the magnitude of the velocity vector. This fixed definition of the speed of light is a result of the modern attempt, in physics, to define the basic unit of length in terms of the speed of light, rather than defining the speed of light in terms of a length.
Different physicists have attempted to measure the speed of light throughout history. Galileo attempted to measure the speed of light in the seventeenth century. A good early experiment to measure the speed of light was conducted by Ole Rømer, a Danish physicist, in 1676. Using a telescope, Ole observed the motions of Jupiter and one of its moons, Io. Noting discrepancies in the apparent period of Io's orbit, Rømer calculated that light takes about 18 minutes to traverse the diameter of Earth's orbit. Unfortunately, this was not a value that was known at that time. If Ole had known the diameter of the Earth's orbit, he would have calculated a speed of 227,000,000 m/s.
Another, more accurate, measurement of the speed of light was performed in Europe by Hippolyte Fizeau in 1849. Fizeau directed a beam of light at a mirror several kilometers away. A rotating cog wheel was placed in the path of the light beam as it traveled from the source, to the mirror and then returned to its origin. Fizeau found that at a certain rate of rotation, the beam would pass through one gap in the wheel on the way out and the next gap on the way back. Knowing the distance to the mirror, the number of teeth on the wheel, and the rate of rotation, Fizeau was able to calculate the speed of light as 313,000,000 m/s.
Léon Foucault used an experiment which used rotating mirrors to obtain a value of 298,000,000 m/s in 1862. Albert A. Michelson conducted experiments on the speed of light from 1877 until his death in 1931. He refined Foucault's methods in 1926 using improved rotating mirrors to measure the time it took light to make a round trip from Mt. Wilson to Mt. San Antonio in California. The precise measurements yielded a speed of 299,796,000 m/s.
There are many sources of light. The most common light sources are thermal: a body at a given temperature emits a characteristic spectrum of black-body radiation. Examples include sunlight (the radiation emitted by the chromosphere of the Sun at around 6,000 K peaks in the visible region of the electromagnetic spectrum), incandescent light bulbs (which emit only around 10% of their energy as visible light and the remainder as infrared), and glowing solid particles in flames. The peak of the blackbody spectrum is in the infrared for relatively cool objects like human beings. As the temperature increases, the peak shifts to shorter wavelengths, producing first a red glow, then a white one, and finally a blue color as the peak moves out of the visible part of the spectrum and into the ultraviolet. These colors can be seen when metal is heated to "red hot" or "white hot". The blue color is most commonly seen in a gas flame or a welder's torch.
Atoms emit and absorb light at characteristic energies. This produces "emission lines" in the spectrum of each atom. Emission can be spontaneous, as in light-emitting diodes, gas discharge lamps (such as neon lamps and neon signs, mercury-vapor lamps, etc.), and flames (light from the hot gas itself—so, for example, sodium in a gas flame emits characteristic yellow light). Emission can also be stimulated, as in a laser or a microwave maser.
Acceleration of a free charged particle, such as an electron, can produce visible radiation: cyclotron radiation, synchrotron radiation, and bremsstrahlung radiation are all examples of this. Particles moving through a medium faster than the speed of light in that medium can produce visible Cherenkov radiation.
Certain chemicals produce visible radiation by chemoluminescence. In living things, this process is called bioluminescence. For example, fireflies produce light by this means, and boats moving through water can disturb plankton which produce a glowing wake.
Certain substances produce light when they are illuminated by more energetic radiation, a process known as fluorescence. This is used in fluorescent lights. Some substances emit light slowly after excitation by more energetic radiation. This is known as phosphorescence.
Phosphorescent materials can also be excited by bombarding them with subatomic particles. Cathodoluminescence is one example of this.
"Lightspeed" redirects here. For other uses, see Lightspeed (disambiguation).
For other uses, see Speed of light (disambiguation).
Light traveling through a medium such as air (for example, this laser) travels slower than light through a vacuum.The speed of light in the vacuum of free space is an important physical constant usually denoted by the letter c.[1] It is the speed of all electromagnetic radiation, including visible light, in free space. It is the speed of anything having zero rest mass.[2] The SI metre is defined such that the speed of light in a vacuum is exactly 299,792,458 metres per second[3] (1,079,252,848.8 km/h or 299,792.458 km/s). The speed of light can be assigned a definite numerical value because the fundamental SI unit of length, the metre, has been defined since October 21, 1983, as the distance light travels in a vacuum in 1/299,792,458 of a second; in other words, any increase in the measurement precision of the speed of light would refine the definition of the metre, but not alter the numerical value of c. The approximate value of 3×108 m/s is commonly used in rough estimates (the error is 0.07%). In imperial units, the speed of light is about 670,616,629.4 miles per hour or 983,571,056.4 feet per second (roughly one foot per nanosecond), which is about 186,282.397 miles per second.
The speed of light when it passes through a transparent or translucent material medium, like glass or air, is less than its speed in a vacuum. The ratio of the speed of light in the vacuum to the observed phase velocity is called the refractive index of the medium. See dispersion (optics). In general relativity c remains an important constant of spacetime, however the concepts of 'distance', 'time', and therefore 'speed' are not always unambiguously defined due to the curvature of spacetime caused by gravitation. When measured locally, light in a vacuum
"Lightspeed" redirects here. For other uses, see Lightspeed (disambiguation).
For other uses, see Speed of light (disambiguation).
Light traveling through a medium such as air (for example, this laser) travels slower than light through a vacuum.The speed of light in the vacuum of free space is an important physical constant usually denoted by the letter c.[1] It is the speed of all electromagnetic radiation, including visible light, in free space. It is the speed of anything having zero rest mass.[2] The SI metre is defined such that the speed of light in a vacuum is exactly 299,792,458 metres per second[3] (1,079,252,848.8 km/h or 299,792.458 km/s). The speed of light can be assigned a definite numerical value because the fundamental SI unit of length, the metre, has been defined since October 21, 1983, as the distance light travels in a vacuum in 1/299,792,458 of a second; in other words, any increase in the measurement precision of the speed of light would refine the definition of the metre, but not alter the numerical value of c. The approximate value of 3×108 m/s is commonly used in rough estimates (the error is 0.07%). In imperial units, the speed of light is about 670,616,629.4 miles per hour or 983,571,056.4 feet per second (roughly one foot per nanosecond), which is about 186,282.397 miles per second.
The speed of light when it passes through a transparent or translucent material medium, like glass or air, is less than its speed in a vacuum. The ratio of the speed of light in the vacuum to the observed phase velocity is called the refractive index of the medium. See dispersion (optics). In general relativity c remains an important constant of spacetime, however the concepts of 'distance', 'time', and therefore 'speed' are not always unambiguously defined due to the curvature of spacetime caused by gravitation. When measured locally, light in a vacuum
Why is it that a beam of light radiates outward, as Young proved? What is really going on? To understand light waves, it helps to start by discussing a more familiar kind of wave -- the one we see in the water. One key point to keep in mind about the water wave is that it is not made up of water: The wave is made up of energy traveling through the water. If a wave moves across a pool from left to right, this does not mean that the water on the left side of the pool is moving to the right side of the pool. The water has actually stayed about where it was. It is the wave that has moved. When you move your hand through a filled bathtub, you make a wave, because you are putting your energy into the water A water wave consists of water molecules that vibrate up and down at right angles to the direction of motion of the wave. This type of wave is called a transverse wave.
Light waves are a little more complicated, and they do not need a medium to travel through. They can travel through a vacuum. A light wave consists of energy in the form of electric and magnetic fields. The fields vibrate at right angles to the direction of movement of the wave, and at right angles to each other. Because light has both electric and magnetic fields, it is also referred to asLight waves come in many sizes. The sizThe wavelengths of the light we can see range from 400 to 700 billionths of a meter. But the full range of wavelengths included in the definition of electromagnetic radiation extends from one billionth of a meter, as in gamma rays, to centimeters and meters, as in radio waves. Light is one small part of the spectrum.
e of a wave is measured as its wavelength, which is the distance between any two corresponding points on successive waves, usually peak-to-peak or trough-to-trough electromagnetic radiation
. The energy travels through the water in the form of the wave.
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Why does light matter?
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light
The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming
Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene
ok,,that's all t.y.
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Why does light matter?
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light
The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming
Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light
The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming
Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light
The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming
Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene
Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
The BoGo Light
The BoGo Light is a scientific, eco-friendly breakthrough that is making an impact worldwide. From Cairo to Cape Town, from the Caribbean to the Amazon, it is improving the lives of individuals, families, and entire villages by replacing costly kerosene, candles, and disposable battery flashlights with an affordable, long lasting, solar flashlight. BoGo means Buy one, Give one. We want our lights to benefit the less fortunate; therefore, with each light purchased in the developed world, a second identical light will be donated to an organization that will distribute it in the developing world with our direct financial support. Give the Gift of Light, and Help Us Change the World!
Environmental Impacts Global Warming
Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene
.,quail assignment 1,.
~is light valuable?~
LIGHT IS VALUABLE
Yes, light is valuable, it is the agent of illumination that stimulates the sense of sight. Light is pale in color. Light is a form of energy. Electrical energy provides us with light. Without light we can't see things especially during nighttime. Light is also a source of light as a candle or lamp used to ignite something. With light human can see the aspect or appearance of other people. Light can make us animated.
Light is an electromagnetic radiation such as ultraviolet, infrared or X-rays. It is the source of brightness and illumination. Light is something that makes vision possible. It is an electromagnetic radiation visible to the human eye. The sensation aroused by stimulation of the visual sense organs is light. It is a particular aspect presented to view.
With light we can be enlightened, we can be informed and instruct. The traffic light is also a light. It is used to prevent traffic in the steets. Sun is the Main Source of Energy on Earth. It supplies heat and light to warm the Earth and sustain life in it.
Light is valuable, so we must take good care of it.
->Suzanne-)
;quail assignment 1.,
->is LIGHT valuable?
->answer:
Light is ELECTROMAGNETIC RADIATION in the wavelength range extending from about 0.4 to about 0.7 or,perharps more properly,the visual response to electromagnetic radiation in this range.By extension,the term is frequently applied to adjacent wavelength range that the eye cannot detect:ULTRAVIOLET LIGHT,infrared light and black light.In addition to wavelength,FREQUENCY,and in hertz,and wave number,inverse unit of length,atre also use to specify and designate the character and quality of the radiation.Associated with wavelength or frequency is the visual response or COLOR.The term monochromatic is applied to the idealized situation in which the length is a beam is all of one wavelength.
Light is characterized not only by wavelength,essentially a temporal quality,but also by state and degree of polarization,a geometric or directional quality,and by intensity,essentially a physical quality.The visual response to intensity is brightness.In the human visual system,at least,there is no counterpart response to the state and degree of polarization,but ample evidence exists that certain arthropods--bees in particular--are sensitive to the state of polarization of sky light.
Quail Assignment 1.,
*Is LIGHT valuable? Justify.
*ANSWER*:
Ma'am this my True answer!
Of course!Yes, LIGHT is valuable! For Light We can't live without light, cause light is the main source of energy,if i'm not mistaken!
LIGHT is everywhere in our world. We need it to see: it carries information from the world to our eyes and brains. Seeing colors and shapes is second nature to us, yet light is a perplexing phenomenon when we study it more closely.
In our daily lives we use light! so it's simple that Light is very valuable! for we can't survive without light!!!
*THATS ALL MA'AM!!
reylan dayuha
Definitely, light is really valuable, especially for us humans. Light is a part of our daily life here in earth. Just imagine a world conquered by darkness. We see things every day, from the moment we get up in the morning until we go to sleep at night. We look at everything around us using light. We use it in almost all important chores we’re doing. We use light that would make our home bright and even just to know if we’re in the right house and not trespassing to other properties. Light will always be a part of our daily activities including decorations or for some beautifications. It adds so much beauty in every party, gatherings or any kind of occasions or fun. We, people could not be able to survive without light. They said that education is the key to success, but, can the students study well if there is no light that would support their home or school studies like reading books, doing different school tasks or having your assignments to be done in home. We appreciate kids' crayon drawings, fine oil paintings, swirling computer graphics, gorgeous sunsets, a blue sky, shooting stars and rainbows. We rely on mirrors to make ourselves presentable and sparkling gemstones to show affection. But did you ever stop to think that when we see any of these things, we are not directly connected to it? We are, in fact, seeing light -- light that somehow left objects far or near and reached our eyes. Light is all our eyes can really see. Without the presence of light, we’ll not be aware if we’re passing in a right path or leading to the wrong one. We’ll not be able to watch out if we’re going to step in a plane floor or in a canal hole. Without light, we’ll not learn how to do many things. Light is our guide wherever we are. Light plays a big role in the development and modernization of the world. Without light, we’ll not be able to see how beautiful a rainbow is or even just to know the color of the trees, the sea, the night sky nor what characteristics a blue color has.
In the dark, you’ll see nothing, but in the presence of light, you’ll see everything.
And that’s how my justifications about the value of light ends.
----CHARLYN V. ZAGADA
IV- QUAIL
Light is life for sure!
by the way light is an electromagnetic wavelength that is visible to the human eye.
LIfe is very important to both living things and nonliving things..why?..because without the presence of light plants cant produce thier own food which is so called photosynthesis..and we humans cant live without light because light make things that sorruonds us visible to our very eyes..if light doesnt existing we humans are like blinds...and we can no longer survive....as what i have said plants cant produce food so if plants cant produce food we humankind will surely die because wer dependent to plants in terms of food..not only humankind but animals as well.aside from that light also is a good vitamin D..it also cures cancer...light is an anti cancer..that is how light very important to every species living in this earth...
my insights about light wont take long...
thats all...
Yours Truly..
--->♥♥_sHaRiLyN_♥♥
Light is life for sure!
by the way light is an electromagnetic wavelength that is visible to the human eye.
LIfe is very important to both living things and nonliving things..why?..because without the presence of light plants cant produce thier own food which is so called photosynthesis..and we humans cant live without light because light make things that sorruonds us visible to our very eyes..if light doesnt existing we humans are like blinds...and we can no longer survive....as what i have said plants cant produce food so if plants cant produce food we humankind will surely die because wer dependent to plants in terms of food..not only humankind but animals as well.aside from that light also is a good vitamin D..it also cures cancer...light is an anti cancer..that is how light very important to every species living in this earth...
my insights about light wont take long...
thats all...
Yours Truly..
--->♥♥_sHaRiLyN_♥♥
yes!Two billion people living in the developing world rely on kerosene lanterns, candles, and single-use battery flashlights for light at night. Not only are these options expensive, dangerous, and harmful to the environment, they also negatively impact health, education, and security. Literacy and Education Our lights provide an opportunity for children to read at night and to extend school hours. This is especially important in developing countries where most children spend all day tending crops, taking care of livestock, or working in cottage industries. Kerosene is increasingly expensive, especially given the recent rise in the price of petrochemicals, so many families cannot afford it. Flashlights are even more expensive, and candles do not provide adequate lighting to read. As a result, many children will never learn to read and will be trapped in a life of poverty. Our lights give them a chance at a better life, thus education is one of the strongest pillars in our vision to light the world.
Our lights help reduce the emission of greenhouse gases. Dr. Evan Mills of the US Department of Energy states that a single kerosene lantern, used four hours a day, emits over 100 kg of the greenhouse gas, carbon dioxide, into the atmosphere each year. As a comparison, the US Environmental Protection Agency (EPA) calculated that a passenger vehicle emits on average 11,450 pounds of carbon dioxide into the atmosphere each year. Therefore, replacing approximately 52 kerosene lanterns in the developing world with solar powered lights is equivalent to removing one vehicle from the roads here in the US.
yes!Light is essential to maintaining normal, healthy physiology. Exposure to sunrise is key to synchronizing our internal body cycles to the external world (so we sleep when it is dark and are alert during the day).
Modern industrial society began to tamper with this system, though. The loss of natural light - in dark apartments, in the workplace, on shift work, etc. - creates a state of light deprivation, making us vulnerable to depressed mood, sleep problems, fatigue, ability to concentrate, and more. Nature, too, posed a new problem when humans began to migrate north, where winter nights are long and dark.
Light levels as measured in lux vary greatly between indoor and outdoor lighting. You can see from the chart below how easy it is to become light deprived in our modern, indoor society.
The importance of full spectrum lighting was demonstrated in 1973 by John Ott, a leading pioneer in the field of lighting. He conducted an experiment in which he compared the effects of full spectrum lighting with cool-white fluorescent lighting on students in separate classrooms in Sarasota, Florida. Concealed, time-lapse cameras recorded sequences of student activity. The results were significant. In cool-white fluorescent light, some students demonstrated hyperactivity, fatigue, irritability, and attention deficits. In contrast, in another class, behavior, and as well as overall academic achievement, showed marked improvement within one month after full spectrum lighting was installed . Furthermore, several learning-disabled students with extreme hyperactivity problems miraculously calmed down, and seemed to overcome some of their learning and reading problems, while in the classrooms with full spectrum lighting.
yes!light is valuable.
why?Anytime we start something new, we have the power to create a fresh version of ourselves. The sum total of what we have learned comes with us into any new situation or relationship. Just like moving into a new home, how often do we really examine the things we are bringing with us?
Do they hold good memories, or are we merely dragging them along because they have always been with us? Boxes of books and magazines we haven’t read. Clothes that fit a body that may never return. Grandmother’s dresser that your sister really wanted and you don’t even like, but coveted the prize she sought?
How much easier life would be if we let go of some of the things we lug around, to make room for the person we are choosing to grow into. There is little room for a plant to grow in a crowded pot.
A new job allows the same possibilities. Bringing what you know into a fresh light with new sources of knowledge and awareness. The opportunity to find challenges to expand your mind and your horizon. To see yourself anew in a different place.
That is one of the hopes of a move, many times. To give ourselves a place to bloom and grow toward a light that may have become hidden. Light is such an important factor in the choosing of most homes. I have noticed that dark homes seem to attract secretive souls, while most people look for an abundance of natural light. Certainly there are times in our lives when we may cling to darkness, but we can always choose to turn on the light....
and this is how my answer ends..............
bow...
definitely yes.Light is an energy producing a sensation of brightness that makes vision possible.without it,we can't see.Light from the sun makes the earth warm enough for life.It is also used by plants in order to produce food for us consumers as well as for their selves.Plants do also give-off oxygen that we breathe in air.Obviously,plants can't produce these vital things without this very significant thing called light.Simply said,life here on earth would not be possible without light. . .
enx...
obviously YES,simply because here in this world where we belong without the presence of "LIGHT" all things can be considered as USELESS.we cant accomplish our daily task(assignment,house hold
chores,etc.)
we human are not the only one who needs light,even plants cant even survive without the presence of light.light is one of the most important factor to consider inorder for the plant to undergo through process called photosythesis so that it will produce food that is commonly needed by humans.<<
tinx yuh?>_<
Yes, it is valuable because light is used in our everyday life. The eyes of the human beings and animals will not function without light. Even plants need sunlight to perform their food making process called photosynthesis. Thus, without light there would be no food for everyone. Without light, darkness will prevail throughout the universe.
1.A short circuit (sometimes abbreviated to short or s/c) allows a charge to flow along a different path from the one intended. The electrical opposite of a short circuit is an open circuit, which is infinite resistance between two nodes. It is common to misuse "short circuit" to describe any electrical malfunction, regardless of the actual problem.
A short circuit is an accidental low-resistance connection between two nodes of an electrical circuit that are meant to be at different voltages. This results in an excessive electric current limited only by the Thevenin equivalent resistance of the rest of the network and potentially causes circuit damage, overheating, fire or explosion. Although usually the result of a fault, there are cases where short circuits are caused intentionally, for example, for the purpose of voltage-sensing crowbar circuit protectors.
2.A FUSE short for 'fusible link', is a type of overcurrent protection device. Its essential component is a metal wire or strip that melts when too much current flows. When the metal strip melts, it opens the circuit of which it's a part, and so protects the circuit from excessive current.When the fuse element blows, the indicating pin extends to activate the micro switch or relay which in turn triggers an event.
3.How do Circuit breakers Work?
The circuit breaker is a simple solution to a potentially deadly problem. See more circuit breaker pictures.The circuit breaker is an absolutely essential device in the modern world, and one of the most important safety mechanisms in your home. Whenever electrical wiring in a building has too much current flowing through it, these simple machines cut the power until somebody can fix the problem. Without circuit breakers (or the alternative, fuses), household electricity would be impractical because of the potential for fires and other mayhem resulting from simple wiring problems and equipment failures.
4.When is there an overload in a circuit?
An electrical overload is a situation where the wiring to or within a machine or system is subjected to a greater electric current load than it was designed to carry, leading to excessive heating of the wires and a possibility of fire. This excessive current load can be a result of electrical insulation failure ( a short circuit) or human error. A correctly designed electrical system incorporates suitable overload protection devices to prevent damage should such a situation occur. Fuses and circuit breakers are most commonly employed for this purpose.
5.Why will too many electrical devices operating at one time often blow a fuse?
This excessive current load can be a result of electrical insulation failure ( a short circuit) or human error. A correctly designed electrical system incorporates suitable overload protection devices to prevent damage should such a situation occur. Fuses and circuit breakers are most commonly employed for this purpose.
6.What are the dangers of short circuit and overload?
In an electrical overload, it leads to excessive heating of the wires and a possibility of fire.
In a short circuit, an accidental low-resistance connection between two nodes of an electrical circuit that are meant to be at different voltages. This results in an excessive electric current limited only by the Thevenin equivalent resistance of the rest of the network and potentially causes circuit damage, overheating, fire or explosion. Although usually the result of a fault, there are cases where short circuits are caused intentionally, for example, for the purpose of voltage-sensing crowbar circuit protectors.
..maAm.. next tym na lang 2ng big questi0n?
...hehehehehe.......
by`,RAPAL
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