A ray of light is incident at an angle of incidence, $i$, on one face of a prism of angle $A$ (assumed to be…

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
  1. $\mu A$
  2. $\frac{\mu A}{2}$
  3. $A / \mu$
  4. $A / 2 \mu$

Solution

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

Asked in: NEET 2012 (Screening)

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