Question

A ray of light is normally incident on one face of an equilateral glass prism. Answer the following:

(a) What is the angle of incidence on the first face of the prism?

(b) What is the angle of refraction from the first face of the prism?

(c) What will be the angle of incidence at the second face of the prism?

(d) Will the light ray suffer minimum deviation by the prism?

Answer 1

(a) If the incident ray is normal to the prism then the angle of incidence is $0^{\circ }$.
(b) In this case the angle of refraction from the first face $r_1$ = $0^{\circ }$ .
(c) As the prism is equilateral so A = ${60}^{\circ }$ and $r_1$​ ​​​​​​=$0^{\circ }$. So at the second face of the prism, the angle of incidence will be ${60}^{\circ }$.
(d) No the light will not suffer minimum deviation.