Four identical point charges are fixed at the four corners of a square of side
PHYSICS · Multi-part · CBSE · Physics · Electric Charges and Fields · Electric Charges and Fields
Problem
Four identical point charges +q are fixed at the four corners of a square of side a. A fifth charge +q is placed at the centre of the square.
(i) Using symmetry, draw the direction of the force exerted on the central charge by each corner charge.
(ii) Show, by vector addition, that the net force on the central charge is zero.
(iii) One of the corner charges (situated at the lower right corner) is now changed to −q while the other three remain +q. Determine the magnitude and direction of the net force acting on the central charge in this new arrangement.
(iv) Comment on how the result in part (iii) would change if, instead, the diagonally opposite corner charge were changed to −q while the other three remained +q.