Question

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 emerge normally from the opposite face. If the refractive index of the prism is $\mu ,$ the angle of incidence i, is nearly equal to:

• A. $\mu A$
• B. $\frac{\mu A}{2}$
• C. $\frac{A}{\mu }$
• D. $\frac{A}{2\mu }$

Answer 1

The correct option is A $\mu A$

For a thin prism [Assumed to be small]
$i+e=A+\delta \left(i\right)$
for minimum deviation since its emerges normally, l = 0
$\delta =(\mu –1)A\left(ii\right)\therefore i+A+\delta Using\left(i\right)and\left(ii\right)i=A+(\mu -1)Ai=A+\mu A–Ai=\mu A$