Question

In Young’s double-slit experiment with monochromatic light, how is fringe width affected, if the screen is moved closer to the slits?

(a) Independent

(b) Remains the same

(c) Increases

(d) Decreases

This question was posed to me in an internship interview.

Enquiry is from Wave Optics in section Wave Optics of Physics – Class 12

Answer 1

Right option is (c) Increases

For explanation I would say: Fringe width is given as:

 β = \(\frac {D\lambda }{d}\)

As the screen is moved closer to the two slits, the distance denoted by D decreases and so fringe width β increase.