Question

Two slits in YDSE are placed 2 millimetre from each other. Interference pattern is observedon a screen placed 2 m from the plane of slits. What is the fringe width for a light of wavelength 400 nm?

Answer 1

Given, `d=2 mm =2xx10^(-3)m,D=2m`
Wavelength, `lambda=400 nm =400xx10^(-9)` m
:. Fringe width, `beta=(lambdaD)/d=(400xx10^(-9))/(2xx10^(-3))=200xx10^(-6)m`