Four point charges are individually brought from infinity and placed at the corners of a square as shown in the figure. Each charge has the identical value +Q. The length of the diagonal of the square is 2a.
-What is the magnitude of the electric field at P, the center of the square?

Question

Four point charges are individually brought from infinity and placed at the corners of a square as shown in the figure. Each charge has the identical value +Q. The length of the diagonal of the square is 2a. 
-What is the magnitude of the electric field at P, the center of the square?

Quizplus · Accepted Answer

The electric field at the center of a square due to charges at the corners cancels out because of symmetry, resulting in a net electric field of zero.

Four Point Charges Are Individually Brought from Infinity and Placed