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| May 2010 |
| Billie Silvey |
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| When I was in second grade, I got my first pair of glasses. They changed my world, or at least my perception of the world. They sharpened the edges of everything. Trees went from blurs of green and dull brown to collections of discrete leaves and textured bark, wood clarified into grains and gradations. And a particular shade of deep rich brown I’d never seen before—or rather, had experienced as a flat muddy gray--suddenly became my favorite color. My world had become richer and more beautiful, thanks to optics. Generally, light travels in a straight line unless it strikes an object which causes it to be bent or absorbed. The lenses of my new glasses bent the light rays in such a way that they focused more sharply on my retina. It is similar to what happens when you focus binoculars or a microscope. The two basic ways light is bent is by reflection or refraction. Reflection occurs when light strikes a mirror or other reflective surface. The angle of incoming light equals the angle of reflected light. Refraction occurs when light traveling through one transparent substance enters another. As light moves from an optically less dense medium, like air, to an optically denser one, like water, it slows. We perceive the different speed of the light as a difference in the size and position of the object. The image we see appears to be bent, or to exist in a different plane. |
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| Electromagnetic Spectrum |
| Albert Einstein once said he wanted the rest of his life to reflect on the nature of light. The implication was that light is so complicated, it could take that long, and still the subject wouldn’t be exhausted.
Einstein was one of a chain of scientists stretching back to Copernicus who worked on light theory and helped developed quantum theory. Quantum mechanics is the essence of every interaction in the universe. Everything was created from light and all interactions proceed by way of light. A quantum is the smallest packet of energy that can be exchanged. It applies both to photosynthesis, the creative power of light to produce and power green plants, and to optics, the exciting of atoms in our eyes that enable us to see. |
| Light can be thought of as either particles or electromagnetic waves. Some principles of optics work using the particle model; others using the wave. Most work for either. Different photons or wavelengths are experienced as different colors, with different amounts of energy. Blue photons have greater energy than red. When an object appears red, all red photons are reflected, while other colors are absorbed. When considered as waves, the distance from one part of the wave to the corresponding part of the next wave makes up a different color. Blues have a shorter wave length than reds. The more intense the light, the greater number of photons. The relationship between energy, wavelength and color are seen in the chart below. |
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| OPTICS |
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