Question

In Fig.22-30, the four particles form a square of edge length a = 5.50 cm and have charges q1 = 8.83 nC, q2 = -6.71 nC, q3 = 8.06 nC, and q4 = -11.6 nC. What is the magnitude of the net electric field produced by the particles at the square's center?

Answer 1

First off, draw the picture out for yourself. Where are the electric field vectors pointing? Draw that center of the square as a dot and all the vectors pointing in the correct directions based on whether the charges are positive or negative.