Optics
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| Discuss Optics WAVE LIKE BEHAVIOUR OF LIGHT
“Is light a wave or a stream of particles?” The fact is that light exhibits behaviors which are characteristic of both waves and particles. Here the focus will be on the wave-like nature of light.
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Light exhibits certain behaviors which are characteristic of any wave and would be difficult to explain with a pure particle-view.
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Light reflects in the same manner that any wave would reflect.
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Light refracts in the same manner that any wave would refract.
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Light reflects in the same manner that any wave would reflect.
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Light refracts in the same manner that any wave would refract.
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Light diffracts in the same manner that any wave would diffract.
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Light undergoes interference in the same manner that any wave would interfere.
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And light exhibits the Doppler effect just as any wave would exhibit the Doppler effect.
Light behaves in a way that is consistent with our understanding of waves. Since light behaves like a wave, one would have good reason to believe that it might be a wave. Here we will focus on three specific behaviors - reflection, refraction and diffraction.
All waves are known to undergo reflection or 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 flat surfaces.
All waves are known to undergo refraction when they pass from one medium to another medium. That is, when a wavefront crosses the boundary between two media, the direction that the wavefront is moving undergoes a sudden change; the path is “bent.” This behavior of wave refraction can be described by 
both conceptual and mathematical principles. First, the direction of “bending” is dependent upon the relative speed of the two media. A wave will bend one way when it passes from a medium in which it travels slow into a medium in which it travels fast; and if moving from a fast medium to a slow medium, the wavefront will bend in the opposite direction. Second, the amount of bending is dependent upon the actual speeds of the two media on each side of the boundary. The amount of bending is a measurable behavior which follows distinct mathematical equations. 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. In fact, a study of the refraction of light reveals that its refractive behavior follows the same conceptual and mathematical rules which govern the refractive behavior of other waves such as water waves and sound waves.
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