Question

Refractive indices of four media A, B, C and D are given below:

Medium	Refractive index
A	1.33
B	1.44
C	1.52
D	1.65

In which of these four media is the speed of light (i) maximum, and (ii) minimum?

Answer 1

The refractive index of a medium is related to the speed of light as follows:

Refractive index =$\frac{\mathrm{speed}\mathrm{of}\mathrm{light}\mathrm{in}\mathrm{vacuum}}{\mathrm{speed}\mathrm{of}\mathrm{light}\mathrm{in}\mathrm{a}\mathrm{medium}}$

Since the speed of light in vacuum is a constant, the refractive index becomes inversely proportional to the speed of light in a medium.

(1)The speed of light is maximum in a medium that has the lowest refractive index, ie., medium A .

(2) The speed of light is minimum in a medium that has the highest refractive index, ie., medium D.