refractive index

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refractive index (n) When light travels from air into a substance its velocity is reduced. The light path is also refracted into the substance, and the relationship between the angle of incidence (i) and the angle of refraction (r) is a constant (Snell's law). This constant (n) is the refractive index of the mineral and is determined by: sin i/sin r = n. The refractive index is also the ratio of the velocity of light in air (V) to the velocity of light in the mineral (v): n = V/v.

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