Question

A prism ABC of angle ${30}^{\circ }$ has its face AC silvered. A ray of light incident at an angle of ${45}^{\circ }$ at the face AB retraces its path after refraction at face AB and reflection at face AC. The refractive index of the material of the prism is

• A. 1.5
• B. $\frac{3}{\sqrt{2}}$
• C. $\sqrt{2}$
• D. $\frac{4}{\sqrt{3}}$

Answer 1

The correct option is C $\sqrt{2}$

A=r+0$\Rightarrow r={30}^{\circ }$

$\therefore \mu =\frac{sini}{sinr}=\frac{sin{45}^{\circ }}{sin{30}^{\circ }}=\sqrt{2}$