Question

. Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 x 108 m s-1.

Answer 1

The speed of light in a medium of refractive index $\mu$ is $\frac{c}{\mu}$, where $c$ speed of light in air.

So, the speed of light in glass having refractive index 1.50 is

$\frac{3*10^8}{1.5} =2*10^8\;m/s$

Answer 2

Explanation:

Refractive index of a medium, nm = Speed of light in vacuum/Speed of light in the medium

Speed of light in vacuum, c = 3 × 108 ms-1

Refractive index of glass, ng = 1.50

Speed of light in the glass, v = Speed of light in vacuum/ Refractive index of glass

= c/ng

=3 × 108/1.50 = 2x 108 ms-1.