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A ray is incident at an angle of incidence $i$ on one surface of a small angle prism (with angle of prism $A$) and emerges normally from the opposite surface. If the refractive index of the material of the prism is $\mu$, then the angle of incidence is nearly equal to:
A
$\frac{2A}{\mu}$
B
$\mu A$
C
$\frac{\mu A}{2}$
D
$\frac{A}{2\mu}$
Detailed Solution
The ray emerges normally from the second surface, so the angle of emergence e = 0 and $r_2 = 0$.
$r_1 + r_2 = A \Rightarrow r_1 = A$
Snell's law at the first surface: $1 \cdot \sin i = \mu\sin r_1 = \mu\sin A$
For small angles ($\sin\theta \approx \theta$): $i = \mu A$