In Young$’$s Experiment, use $632\mathrm{.}8$ nm He$-$Ne laser illuminating the source slit. The distance between the two slits S$1$ and S$2$ is $0\mathrm{.}5$ mm$.$ The screen is $2$ m away from them. How far will the consecutive maxima of the fringe be separated on the screen? If you are using an electron gun rather than the laser and you can change the distance between the two slits, how far you need to separate them in order to get similar fringe? Given the acceleration voltage for the electron is $2000$ V$.$