question_answer

Interference fringes were produced in Young's double slit experiment using light of wave length\[5000\text{ }A{}^\circ \]. When a film of material \[2.5\times {{10}^{-3}}\text{ }cm\]thick was placed over one of the slits, the fringe pattern shifted by a distance equal to 20 fringe width. What is the refractive index of the material of the film?

Answer:

1.4