Question

A light ray is incident perpendicular to one face of a 90° prism and is totally internally reflected at the glass-air interface. If the angle of reflection is 45°, we conclude that the refractive index n as

(a) n < 1/√2

(b) n > √2

(c) n > 1/√2

(d) n < √2.

Answer 1

Correct Option (b) n > √2

Explanation:

For total internal reflection from glass-air interface, critical angle C must be less than angle of incidence