Question

a) Define refractive index of a transparent medium. What is its unit ? Which has higher refractive index, glass or water ? (b) A ray of light travelling in air enters obliquely into water. Does the light ray bend towards or away from the normal (with referance to refractive index).

Answer 1

a)Refractive index of a medium is defined as the ratio of the speed of light in vacuum to the speed of light in that medium.
It has no units as it is the ratio of two similar quantities.
Glass has higher refractive index.
b)the light ray bends towards the normal because water has higher refractive index than air because when speed of light increase refractive index decreases.