Question

Four point charges q_A = 2 µC, q_B = -5 µC, q_C = 2 µC and q_D = -5 µC are located at the corners of a square ABCD of side 10cm. What is the force of a charge of 1 µC placed at the centre of the square?

Answer 1

Consider the square ABCD of each side 10cm and centre O. The charge of 1 µC is placed at point O. The charge of 1 µC is placed at point O.

∴ OA = OB = OC = OD

Since q_A = q_C, the charge of 1 μ C experiences

equal and opposite forces due to the charges q_A and q_C. Similarly, the charges of 1 µC experiences equal and opposite forces F_fi and F_d due to the charges q_B and q_D. Hence, the net force on the charge of 1pC due to the given arrangement of the charges is zero.