P$9$: In the Young's double slit experiment with electrons, the separation between the two slits is $d$ along the $y-$direction. If we want to be sure that an electron goes through a particular slit, $y$ should be smaller than $\frac{d}{2}.$ Using uncertainity relation $y{p}_y\frac{}{2},$ show that this will create enough uncertainity in the $p_r,$ so that the electron would land on the screen over a width larger than the fringe width of the intereference pattern. Thus the interefernce pattern will be destroyed.