A ray of light enters benzene from the air. If the refractive index of benzene is 1.50, by what per cent does the speed of light reduce on entering the benzene?

OR

For the same angle of incidence in media A, B and C, the angles of refraction are 20°, 30° and 40° respectively. In which medium will the velocity of light be maximum? Give reason in support of your answer.

Given:

Refractive Index of Benzene = 1.5

Speed of Light in Air = 3 × 10⁸ m/s

To find: Percentage Reduction in Speed of Light

= 2 × 10⁸ m/s

= 66.7%

Therefore, Percentage reduction in the speed of light = 66.7%.

OR

The Snell’s Law of refraction can be stated as follows:

Where i is the angle of incidence and r is the angle of refraction.

Refractive Index of the medium can also be defined as the ratio of the speed of light in the air to the speed of light in the medium.

Where c is the speed of light in air and v is the speed of light in the medium

Given the angle of incidence is constant and the speed of light in air is also constant

sin [r] × c = sin [i] × v

If we remove the constants then

sin [r] α v.

Hence in medium C, the ray of light will travel with the fastest speed as in this medium the angle of refraction is maximum.