Four point charges are individually brought from infinity and placed at the corners of a square. Each charge has the identical value Q. The length of the diagonal of the square is 2a. What is the electric potential at the center of the square

Complete Question

The complete question is shown on the first uploaded image  

The electric potential is  

Explanation:

From the question we are told that

     The charge on each point  is  +Q

      The length of the diagonal is  2a

Generally the electric potential is mathematically represented as

Here r is the distance from each vertices of the square to the center P which is evaluated as

  So the potential at the center due to one charge is evaluated as

Given that there are four charge the net electric potential at the center P will be