Question

A ray of light is incident normally on a plane glass slab. What will be (i) the angle of refraction, and (ii) the angle of deviation for the ray?

Answer 1

The ray of light which is incident normally on a plane glass slab passes undeviated. That is such a ray suffers no bending at the surface because here the angle of incidence is $0^{\circ }$. Thus if the angle of incidence ∠i = $0^{\circ }$,
(i) then the angle of refraction ∠r = $0^{\circ }$.
(ii) And the angle of deviation of the ray will also be $0^{\circ }$.