Question

In Young's double slit experiment using monochromatic light of wavelength $600$nm, interference pattern was obtained on a screen kept $1.5$m away from the plane of the two slits. Calculate the distance between the two slits, if fringe separation/fringe width was found to be $1.0$mm.

Answer 1

Given: $\lambda =600$nm.
$=600\times {10}^{-9}$m
$D=1.5$m
$d=?$
$\omega =1$mm.
$=0.001$m or $1\times {10}^{-3}$m
$\omega =\frac{D\lambda }{d}$
$1\times 10-3=\frac{1.5\times 600\times {10}^{-9}}{d}$
$d=9\times {10}^{-4}$m.