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 refractive index of any medium with respect to vacuum is defined as

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

now its given that refractive index of vacuum with respect to glass is 2/3

`(2)/(3) = (speed of light in glass)/(speed of light in air)`

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

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

Part (ii)

Now similarly we have

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

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

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

now we will have

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