Question

The index of refraction for water is about 4/3. What happens to light when it travels from air into water?

Answer 1

Answer:

The light slows down to a speed equal to 3/4 of its original value

Explanation:

The speed of light in a medium is given by:

$v=\frac{c}{n}$

where

$c=3.0\cdot 10^8 m/s$ is the speed of light in a vacuum

n is the index of refraction of the medium

For light entering air, we have that the light enters a medium with index of refraction of

$n=\frac{4}{3}$

Therefore, its speed changes as follows

$v=\frac{c}{\frac{4}{3}}=\frac{3}{4}c=\frac{3}{4}(3\cdot 10^8 m/s)=2.25\cdot 10^8 m/s$