Question

A ray of light strikes a glass plate at an angle $60^{\circ}$. If the reflected and refracted rays are perpendicular to each other, the index of refraction of glass is

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

Answer 1

Answer: (A)

Angle $N'O T=30^{\circ}$ this is found by geometry after putting angle between refleted and transmitted ray equal to $90^{\circ}$
$\mu=\frac{\sin i}{\sin r}=\frac{\sin 60^{\circ}}{\sin 30^{\circ}}$
or $\mu=\frac{\sqrt{3}}{2} \times \frac{2}{1}$
$\therefore \mu=\sqrt{3}$