Apoorva Arora
Last Activity: 11 Years ago
Let us take a small length element dx the charge on it is dq
so the potential due to this small element is given by
where

a= distance between z=d and z=z (some arbitrary value)
x the distance between the length element dx and z=d
hence
therefore potential at z=4d
and at z= 3d
and hence the difference

is the potential difference
Thanks and Regards
Apoorva Arora
IIT Roorkee
askIITians Faculty