question_answer

A monochromatic beam of light is used for the formation of fringes on the screen by illuminating the two slits in the Youngs double slit interference experiment. When a thin film of mica is interposed in the path of one of the interfering beams then:

A) the fringe width increases

B) the fringe width decreases

C) the fringe width remains the same but the pattern shifts

D) the fringe pattern disappears

Correct Answer: C

Solution :

                When a thin transparent plate of mica is introduced is the path of one of the two interfering light beams (as shown) then the entire fringe pattern is displaced towards the beam in the path of which the plate is introduced, but the fringe width is not changed.