If the light ray incident on a plane interface between two dielectric transparent media, Then the Snell's law of refraction states that the incident ray, the refracted ray and the normal to the interface, all lie in the same plane. Relation between them is given by,
Where θ1 is angle between the incident ray and normal to the interface and θ2 is the angle between the refracted ray and normal to the interface. n1 and n2 are refractive indices of the media 1 and 2 respectively.
Hence the Snell's law of refraction predicts that the light ray always deviates more towards normal in the optically denser medium (medium of higher refractive index) and away from the normal in the optically rarer medium (medium of lower refractive index). In figure n2>n1.
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