Question

A ray of light is incident on one face of an equilateral prism. When the angle of incidence is ${90}^{\circ }$, the refracted ray from the first face goes undeviated from the second face. Find the refractive index of the material of the prism.

• A. 1.15

Answer 1

The correct option is A 1.15

$\text{Here}{r}_2=0^{\circ },A={60}^{\circ }$
$\text{As}A=r_1+r_2$
$\Rightarrow r_1={60}^{\circ }$
$\text{sin}i=\mu \text{sin}{r}_1$
$\text{sin}{90}^{\circ }=\mu sin{60}^{\circ }$
$\Rightarrow \mu =\frac{2}{\sqrt{3}}$