Question

The light enters from air to glass having refractive index 1.5. The speed of light in glass is: 

a) 3 X 10⁸ m/s 

b) 2 X 10⁸ m/s 

c) 1.5 X 10⁸ m/s 

d) 2.25 X 10⁸ m/s

Answer 1

Correct answer is (b) 2 X 10⁸ m/s 

Explanation: Speed of light in glass = speed of light in air / refractive index of glass

= 3 X 10⁸ m/s / 1.5

= 2 X 10⁸ m/s 

The speed of light in glass is 2 X 10⁸ m/s.