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 × 108

m s−1

.​

Answer 1

ANSWER AND EXPLANATION

Light travels at approximately 300,000 kilometers per second in a vacuum, which has a refractive index of 1.0, but it slows down to 225,000 kilometers per second in water  and 200,000 kilometers per second in glass.

Answer 2

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 m/s

→Refractive index of glass (ng) = 1.50

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

=$\large\mathrm\purple{c/ng}$

=3 × 108/1.50 = 2x 108 ms-1.