Question

A prism made up of flint glass is such that the incident ray does not emerge from the second surface. Critical angle for flint glass is ${36}^{\circ }$. Then, refracting angle A must be

• A. ${37}^{\circ }$
• B. ${54}^{\circ }$
• C. ${71}^{\circ }$
• D. ${73}^{\circ }$

Answer 1

The correct option is D ${73}^{\circ }$

In the prism the to occur total internal reflection the refracting angle a must be more than twice the critical angle of the prism material. In this case, critical angle for flint glass is 36 so the refracting angle.
A must be greater than twice of the critical angle that is it must be greater than 72.

Option (D) is correct.