Question

A ray of light falls on a transparent sphere with centre at $C$ as shown in figure. The ray emerges from the sphere parallel to line $AB$. The refractive index of the sphere is

• A. $\sqrt{2}$
• B. $\sqrt{3}$
• C. 3/2
• D. 1/2

Answer 1

Answer: (B)

Deviation by a sphere is $2(i-r)$
Here deviation $\delta=60^{\circ}=2(i-r)$
or $i-r=30^{\circ}$
$\therefore r=60^{\circ}-30^{\circ}=30^{\circ}$
$\therefore \mu=\frac{\sin i}{\sin r}=\frac{\sin 60^{\circ}}{\sin 30^{\circ}}=\sqrt{3}$