A light ray enters from medium A to medium B

A light ray enters from medium A to medium B as shown in Figure.

The refractive index of medium B relative to A will be

  1. greater than unity
  2. less than unity
  3. equal to unity
  4. zero

Answer

Since light rays in medium B goes towards normal. So it has greater restrictive index and lesser velocity of light with respect to medium A. So refractive index of medium B with respect to medium A is greater than unity.

The correct option is A.