Question

A ray $OP$ of monochromatic light is incident on the face $AB$ of prism $ABCD$ near vertex $B$ at an incident angle of ${60}^{\circ }$ (see figure). If the refractive index of the material of the prism is $\sqrt{3}$, which of the following is (are) correct?

• A. The ray gets totally internally reflected at face $CD$
• B. The ray comes out through face $AD$
• C. The angle between the incident ray and the emergent ray is ${90}^{\circ }$
• D. The angle between the incident ray and the emergent ray is ${120}^{\circ }$

Answer 1

Answer: (A), (B), (C)

The correct options are
A The ray gets totally internally reflected at face $CD$
B The ray comes out through face $AD$
C The angle between the incident ray and the emergent ray is ${90}^{\circ }$

Using Snell's law, ${\sin }^{-1}\frac{1}{\sqrt{3}}<{\sin }^{-1}\frac{1}{\sqrt{2}}$
Net deviation is ${90}^{\circ }$.