• # question_answer A prism ABC of angle $30{}^\circ$ has its face AC silvered. A ray of light incident at an angle of ${{45}^{o}}$ 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)  $\frac{4}{3}$

$A=r+0\Rightarrow r={{30}^{o}}$ $\therefore$ $\mu =\frac{\sin i}{\sin r}=\frac{\sin {{45}^{o}}}{\sin {{30}^{o}}}=\sqrt{2}$