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

Options

A. The fringe width increases
B. The fringe width decreases
C. The fringe width remains he same but the pattern shifts
D. The fringe pattern disappeasrs.

Answer

C

Explanation

The presence of thin mica in the path of one of the interfering beams changes only the path difference between the beams due to which the pattern shifts upwards.But the fringe width remains the same.As mochromatic light is used,one cannot make out which is the central shift as all the fringes are having the same colour and intensity.