Question

A Ray of light enters into benzene from air if the refractive index of benzene is 1.50 by what percent does the speed of light reduce on entering the Benzene

Answer 1

refractive index is the ratio of speed in air by speed in medium

as you all know light is fastest in vacuum and only slows down in other medium

this explains why refractive index can't be less than 1

now let speed in benzene be v

c/v = refractive index = 1 .5

where c is speed of light in vacuum = 3*10^8 m/s

so v = c*2/3

v= 2 * 10^8

now reduction is final - initial = c-v= 10^8

percentage reduction = (10^8/3*10^8 )*100

= 1/3*100

= 33.33%

Answer 2

Answer:

33.3 % .

Explanation:

Given :

Refractive index of benzene = 1.50

We know :

Speed of light = 3 × 10⁸ m / sec

We know formula for n :

n = speed of light in vacuum / speed of light in benzene

n = c / v

1.5 = 3 × 10⁸ / v

v = 2 × 10⁸ m / sec

Now ,

Percentage ( % ) decrease = 1  × 10⁸ / 3  × 10⁸  × 100 %

% decrease = 33.3 % .