Three equal negative point charges -q are placed at three of the corners of a square of side d as shown in the figure.Which one of the arrows shown represents the direction of the net electric field at the center of the square?
A)A
B)B
C)C

Question

Three equal negative point charges -q are placed at three of the corners of a square of side d as shown in the figure.Which one of the arrows shown represents the direction of the net electric field at the center of the square? 
A)A 
B)B 
C)C

Quizplus · Accepted Answer

At the center of the square, the electric field vectors due to each of the three charges q at three of the corners will be directed along the line joining the center and the charge. Since these three vectors are equal in magnitude but opposite in direction, they will cancel each other out in pairs, leaving one field vector directed along the diagonal of the square. The arrow pointing in the direction of the diagonal is represented by choice C, which shows the net electric field at the center of the square. Therefore, the correct choice is C.

Three Equal Negative Point Charges -Q Are Placed at Three