Question

The refractive index of water with respect to vacuum is 4/3 and refractive index of vacuum with respect to glass is 2/3. If the speed of light in glass is 2x 108m/s, find the speed of light in i) Vacuum ii) water

Answer 1

As we know that

`\mu = (speed of light in air)/(speed of light in medium)`

now for the first part we know that

refractive index of vacuum with respect to glass is 2/3

speed of light in glass is
`2 * 10^8 m/s`

now we will have

`(2)/(3) = (2* 10^8)/(c)`

`c = 3 * 10^8 m/s`

Part b)

Now similarly we can say

`\mu = (speed of light in air)/(speed of light in medium)`

here refractive index of water with respect to vacuum is 4/3

`(4)/(3) = (3 * 10^8)/(v)`

now we will have

`v = 2.25 * 10^8 m/s`