PHYSICS · Multi-part · CBSE · Physics · Electric Charges and Fields · Electric Charges and Fields
Problem
Four identical positive point charges, each of magnitude +q, are fixed at the corners of a square of side length a that lies in a horizontal plane. A small test charge of magnitude +q0 is placed at the geometric center of the square. Gravity is negligible compared with electrostatic interactions in this problem.
(a) Describe the magnitude and direction (if any) of the net electrostatic force experienced by the test charge while it remains exactly at the center of the square. Provide a clear conceptual justification for your answer.
(b) The test charge is displaced a very small distance toward the lower-left corner of the square and then released from rest. Qualitatively describe the direction of the net electrostatic force acting on the charge immediately after it is released, and explain whether the charge will tend to accelerate back toward the center.
(c) The point charge at the lower-left corner is now replaced by a charge of magnitude −q. Without performing explicit calculations, state whether the net force on the test charge (still located at the center) is zero or non-zero, and indicate its general direction. Justify your reasoning based on symmetry and vector addition principles.