A ray of light is incident at an angle of incidence, $i$, on one face of a prism of angle $A$ (assumed to be small) and emerges normally from the opposite face. If the refractive index of the prism is $\mu$, the angle of incidence $i$, is nearly equal to

• Correct answer
  A

  $\mu A$
• B

  $\frac{\mu A}{2}$
• C

  $A / \mu$
• D

  $A / 2 \mu$

Solution

Refractive index $\begin{gathered} \mu=\frac{\sin i}{\sin r} \\ \mu=\frac{\sin i}{\sin A} \end{gathered}$ In case of small angle. $\begin{aligned} \mu & =\frac{i}{A} \\ i & =\mu A \end{aligned}$

Hence, the correct answer is option: 'A'.