If the speed of light in air is 3 x 108 m/s, the speed of light in glass

If the speed of light in air is 3 x 108 m/s, the speed of light in glass (with refractive index 1.5) would be

  1. 4.5 x 108 m/s
  2. 1.5 x 108 m/s
  3. 2 x 108 m/s
  4. 3 x 108 m/s

Answer

Refractive index of glass with respect to air = 1.5

1.5 = Speed of light in air / Speed of light in glass

Speed of light in glass = 3 x 108 / 1.5 = 2 x 108 m/s

The correct option is C.