When light passes form one
medium to another of different refractive index its speed changes. It moves more slowly in a
material of higher refractive index than it does in a material of low refractive index.
The light moves slower in the material of higher refractive index (medium 1).
n1sinθ1 = n2sinθ2 and n1/n2 = c2/c1
therefore: c2sinθ1 = c1sinθ2
Refractive index = velocity in free space (usually taken as air)/velocity in the material
The ratio of the speeds in the two materials is the inverse ratio of the refractive indices of the two materials
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