Question

(a) A ray of monochromatic light is incident on one of the faces of an equilateral triangular prism of refraction angle A. Trace the path of ray passing through the prism. Hence derive an expression for the refractive index of the material of the prism in terms of the angle of minimum deviation and its refracting angle.

Answer 1

Monochromatic light enters an equilateral prism made of glass in such a way that after refraction at the first surface light travels parallel to the base of the prism and is refracted on the second surface. This implies that light is refracted twice.

The angle of deviation as indicted in the image diagram attached is the angle through which the emergent ray deviates from the direction of the incident ray.