Question

The refractive index of glass for light going from air to glass is $\frac{3}{2}.$ Glass to air will be :

(a) $\frac{2}{3}$

(b) $\frac{4}{5}$

(c) $\frac{4}{6}$

(d) $\frac{5}{2}$

Answer 1

Step 1: Given that:

The refractive index of glass for light going from air to glass(${}^a{n}_g$ )= $\frac{3}{2}$

Step 2: Calculation of refractive index for light going from glass to air:

According to the reversibility of light,

1. The refractive index of a medium (1) with respect to the medium (2) that is ${}^1{n}_2$ is reciprocal of the refractive index of the medium (2) with respect to the medium (1) that is ${}^2{n}_1$.

Mathematically; ${}^1{n}_2=\frac{1}{{}^2{n}_1}$

Thus,

The refractive index of glass for light going from glass to air(${}^g{n}_a$ ):=$\frac{1}{{}^a{n}_g}$

${}^g{n}_a$ = $\frac{1}{\frac{3}{2}}$

${}^g{n}_a$ = $\frac{2}{3}$

Thus,

The refractive index for light going from glass to air is $\frac{2}{3}$ .