Q. A prism of angle $30{^\circ}$ is silvered at one side. A ray of light incident at an angle $45{^\circ}$ is reflected back from the silvered surface. The refractive index is
A) $\sqrt{2}$
B) $2\sqrt{2}$
C) $\sqrt{3}$
D) $5\sqrt{3}$
Explanation
(a) $A = r + 0 \Longrightarrow r = 30{^\circ}$
From Snell’s law at surface $AB$
$\mu = \frac{\sin i}{\sin r}$
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$or\ \mu = \frac{\sin{45{^\circ}}}{\sin{30{^\circ}}} = \frac{2}{\sqrt{2}} = \sqrt{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.