Four point charges each having charge Q are located at the corners of a square having sides of length a.
(a) Find symbolic expressions for the work required to bring a fifth charge q from infinity to the center of the square.

Explanation:

Given

Four Point charges are Placed at the corner of a square with side length a

Length of diagonal

Distance of charge from center

Potential at the center due to four charges is given by

as all the four charges are equal and placed symmetrical about center

Work done required to bring a fifth charge q from infinity to the center of the square

beta is electron from nucleus

something from nucleus has changed, but charge must be same for cons of charge