Question

A ray of light, incident on the face AB of a prism (made from a material of refractive index μ) gets refracted there and falls on its other face AC. If it were to go grazing along this face, the angle of refraction (< r), at the face AB, would equal

Answer 1

Correct option: (4)

Explanation: 

It is clear that the angle of emergence, at the face AC, is 90°. The angle of incidence (say r’), at the face

AC, must equal the critical angle (= sin^-1 1/µ) for the material of the given prism.