(a) What is the speed of light in water of refractive index `4//3`?
(b) Light travels in a medium with a velocity of `2xx10^(8)m//s`. What is refractive index of the medium?

Explanation

(a) From `v=c/n, v=(3xx10^(8)m//s)/(4//3)=2.25xx10^(8)m//s`. , (b) From `n=c/v=(3xx10^(8)m//s)/(2xx10^(8)m//s)=1.5`.