What is the law of reflection?

The angle of incidence is equal to the angle of reflection.

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At what angle should the normal line be drawn to a boundary?

90°

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What is the equation that links the refractive index of a substance (n), speed of light (c) and the speed of light in a substance (v)?

n = vc​


n = refractive index

c = speed of light in a vacuum = 3 x 108 ms-1

v = speed of light in substance (ms-1)

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What is meant by refraction?

Refraction is the phenomenon where light changes direction as it passes the boundary between different substances.

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What is the formula linking refractive index (n), angle of incidence (i) and angle or refraction (r)?

n = sin (r)sin (i)​

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Which way does light bend when it travels from a more optically dense medium to a less optically dense medium?

Away from the normal.

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What is the Snell's law equation that links the refractive indices of the materials (n1 and n2), the angle of incidence (i) and the angle of refraction (r)?

n1​ sin (i) = n2​ sin (r)


n1 = refractive index of first substance

i = angle of incidence (°)

n2 = refractive index of second substance

r = angle of refraction (°)

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Which way does light bend when it travels from a less optically dense medium to a more optically dense medium?

Towards the normal.

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What is the critical angle in total internal reflection?

The angle of incidence which causes refraction at 90°.


Any angle greater than the critical angle will result in total internal reflection.

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What are the two conditions for total internal reflection to occur?

  1. Light must be travelling from a more optically dense substance to a less optically dense substance
  2. The angle of incidence must exceed the critical angle

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What is the equation that links refractive index (n) and the critical angle (c)?

sin (c) = n1​

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