Refracting angle o f a prism `A=60^@` and its refractive index is `n=3//2`. What is angle of incidence i to get minimum deviation. Also, find the minimum deviation. Assume the surrounding medium to be air `(n=1)`.

Explanation

For minimum deviation,
`r_(1) = r_(2) = (A)/(2) = 30^(@)`
applying Snell's law at `l` surface
`1xx sin I = (3)/(2) sin 30^(@) rArr I = sin^(-1) ((3)/(4)) rArr delta_(min) = 2sin^(-1) ((3)/(4)) -60^(@)`