1. The problem statement, all variables and given/known data Calculate the electric field at the center of a square with side length .360 m. The charges, clockwise from top left on the corners, are Q1 = 4 x 10^-6, Q2 = 3 x 10^-6, Q3 = 1 X 10^-6 and Q4 = 5 x 10^-6 Coulombs. 2. Relevant equations E = kq/r^2 where k = Coloumb's constant, q = charge and r = distance between two points 3. The attempt at a solution I'm really stuck on this problem. I've tried multiple guesses, all wrong, and I'm at what I assume is essentially the penultimate step, but must be missing an understanding. Using Pythagorean Theorem to get the diagonal of the square, and dividing that by 2, I calculated the distance from each charge to the center to be .2545. I worked out the effect each charge has on the center as follows: EQ1 = 5.55 x 10^5 N/C EQ2 = 4.16 x 10^5 N/C EQ3 = 1.39 x 10^5 N/C EQ4 = 6.94 x 10^5 N/C Here is where I'm having trouble. I know electric field is a vector, and as such, I must sum the above vectors to get the net field at the center. But no matter what way I add them, it turns out to be wrong. I've tried considering opposite corners to have opposite directions and subtracting them, simply adding them all up, and various other methods. Nothing works. Can anyone offer advice as to how I can finish this problem?