(a) The refractive index of glass is 1.5. What is the speed of light in glass? `("Speed of light in vacuum is "3.0 xx 10^(8) m s^(-1))`
(b) Is the speed of light in glass independent of the colour of light? If not, which of the two colours red and violet travels slower in a glass prism?

Explanation

We have
`mu=(speed of light in vacuum)/(speed of light in the material)`
Thus, speed of light in glass
`=(sped of light in vacuum)/mu`
`=(3.0xx10^8ms^-10/1.5=2.0xx10^8ms^-1`.