Physics - Wave Optics Question with Solution | TestHub

The fringe width in a double slit experiment is given by $W=\frac{\lambda D}{d}$

Given that the distance between the slits is increased $10$ times, $d^{\prime }=10d$

The distance from the screen is halved, $D^{\prime }=\frac{D}{2}$

The new fringe width is $W^{\prime }=\frac{\lambda D^{\prime }}{d^{\prime }}$

Substituting the values, we get:

$W^{\prime }=\frac{\lambda \left(\frac{D}{2}\right)}{10d}=\frac{1}{20}\left(\frac{\lambda D}{d}\right)=\frac{W}{20}$

The fringe width becomes $\frac{1}{20}$ times.

Answer: becomes $\frac{1}{20}$ times.