Question

Four points charges -Q,-q,2qAND 2Q are placed ,one at each corner of the square .The relation between Q and q FOR WHICH THE POTENTIAL AT THE CENTRE OF THE SQUARE IS ZERO IS??

Answer 1

`Q+q=0`

Explanation:

Let the distance of the center from each corner be `a`. The the potential at the center is

`V = 1/(4pi epsilon_0)((-Q)/a+(-q)/a+(2q)/a+(2Q)/a) =1/(4pi epsilon_0)(Q+q)/a`

This is zero if

`Q+q=0`