Refraction of light at the interface between two media of different refractive indices, with n2 > n1. Since the phase velocity is lower in the second medium (v2 < v1), the angle of refraction ?2 is less than the angle of incidence ?1; that is, the ray in the higher-index medium is closer to the normal.

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Refraction of light at the interface between two media of different refractive indices, with n2 > n1. Since the phase velocity is lower in the second medium (v2 < v1), the angle of refraction ?2 is less than the angle of incidence ?1; that is, the ray in the higher-index medium is closer to the normal.