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INTRODUCTIONTO LIGHTSWhat is Light?Light is a form of energy.Light has properties of both a wave and a particle.Light waves move as transverse waves.These waves move extremely fast in straight paths called raysLight waves do not need a medium through which to move.Light waves are electromagnetic waves
Light Waves vs. Sound WavesLIGHT WAVESIt move as transverse wavesIt do not need a medium to travel; they can travel through empty space
Light Waves vs. Sound WavesSOUND WAVESAre compressional, or longitudinalSound waves need a medium to travel; they cannot travel through empty space.
BEHAVIORAL CHARACTERISTICS OF LIGHTLight exhibits certain behaviors that are characteristic of any wave and would be difficult to explain with a purely particle-view. Light reflects in the same manner that any wave would reflect. Light refracts in the same manner that any wave would refract. Light diffracts in the same manner that any wave would diffract. Light undergoesinterferencein the same manner that any wave would interfere. And light exhibitsthe Doppler effectjust as any wave would exhibit the Doppler effect. Light behaves in a way that is consistent with our conceptual and mathematical understanding of waves. Since light behaves like a wave, one would have good reason to believe that it might be a wave.REFLECTIONAll waves are known to undergoreflectionor the bouncing off of an obstacle. Most people are very accustomed to the fact that light waves also undergo reflection. The reflection of light waves off of a mirrored surface results in the formation of an image. One characteristic of wave reflection is that the angle at which the wave approaches a flat reflecting surface is equal to the angle at which the wave leaves the surface. This characteristic is observed for water waves and sound waves. It is also observed for light waves. Light, like any wave, follows the law of reflection when bouncing off surfaces.
REFRACTIONAll waves are known to undergorefractionwhen they pass from one medium to another medium. That is, when a wave front crosses the boundary between two media, the direction that the wave front is moving undergoes a sudden change; the path is "bent.Refraction is the bending of light rays when passing through a surface between one transparent material and another.This behavior of wave refraction can be described byboth conceptual and mathematical principles. First, the direction of "bending" is dependent upon the relative speed of the two media. Second, the amount of bending is dependent upon the actual speeds of the two media on each side of the boundary.These equations are based upon the speeds of the wave in the two media and the angles at which the wave approaches and departs from the boundary. Light, like any wave, is known to refract as it passes from one medium into another medium.
DIFFRACTIONIt involves a change in direction of waves as they pass through an opening or around an obstacle in their path.When light encounters an obstacle in its path, the obstacle blocks the light and tends to cause the formation of a shadow in the region behind the obstacle. Light does not exhibit a very noticeable ability to bendaround the obstacle and fill in the region behind it with light. Nonetheless, light does diffract around obstacles. In fact, if you observe a shadow carefully, you will notice that its edges are extremely fuzzy.
References:http://camillasenior.homestead.com/optics3.htmlhttp://www.physicsclassroom.com/Class/light/u12l1b.cfm
