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Reflection

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Reflection Reflection

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"Reflection is a change in direction of a wave upon striking the interface between two materials."(#1.)

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Total Internal Reflection

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Total Internal Reflection Total Internal Reflection

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is a phenomena which occurs when light propagates from the medium with greater index of refraction in the medium with lower index of refraction. From Snell's law we know that the light in this case refracts away from the normal. That means that there is an angle of incidence for incoming ray where all the light will not leave the medium with higher index of refraction, but instead it will reflect in direction perpendicular to the normal (i.e. in the plane of the boundary).  If the angle of incidence is larger than this critical angle, all the light is reflected back into the medium with higher index of refraction. We can obtain value for critical angle mathematically using following equation: 

Where n2 is index of refraction of the medium with higher lower index. 

Fig. 5. Multiple total internal reflections (#4.)

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Dispersion of Light

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Dispersion Dispersion

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The index of refraction of medium is dependent on the frequency of incoming light ray. Therefore if light with with wide frequency spectrum (such as daylight) enters for example glass prism, the component frequency bands (for visible colors) will diffract under slightly different angles. The result is light divided into colorful "strip" for each of basic colors. The very same effect is behind rainbow which is natural occurrence of dispersion. 

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Refraction

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Refraction Refraction

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It’s the change in direction of a wave due to a change in its medium. It is essentially a surface phenomenon. This is most commonly observed when a wave passes from one medium to another at any angle other than 90° or 0°. (#6.)
Explanation:

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• First video explains shortly speed of light in different mediums.
• Second video gives a brief description of how and why refraction happens.

References:

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<ac:structured-macro ac:name="anchor" ac:schema-version="1" ac:macro-id="fd8e36ff8443a567-c320ae50-4b1c4bbf-a8848b78-6ea1b70dad27bb3c125956ed"><ac:parameter ac:name="">3.</ac:parameter></ac:structured-macro> 3. _Reflection and Its Importance_. (n.d.).  Retrieved December 10, 2012, from Physics Classroom: \[http://www.physicsclassroom.com/class/refln/u13l1c.cfm\]

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