1. The problem statement, all variables and given/known data #1: Four point charges have the same magnitude of 6.80 x 10^-12 C and are fixed to the corners of a square that is 1.0 cm on a side. Three of the charges are positive and one is negative. Determine the magnitude of the net electric field that exists at the center of the square. #2: The magnitude of each of the charges in the figure is 7.50 10-12 C. The lengths of the sides of the rectangle are 3.00 cm and 4.50 cm. Find the magnitude of the electric field at the center of the rectangle in figures a and b. 2. Relevant equations E = k q/r^2 3. The attempt at a solution Ok so i have been ALL over the forums here and looking at other examples and still nto getting it. I am on my final response...i am normally very smart so i don't get why i am sucking in this section. #1: I looked at it and said that the two positive forces opposite each other would negate each other leaving only the negative charge and the one positive charge across from it. With that I said E = k*6.8e-12/ (1/2 of 1 * sqrt(2) since it is a half of a diagonal in a square) i got .1224 for each charge...added the two together and it was wrong. I also tried an instance where i did it with all 4...so it was 4 * k * q / (.5*sqrt(2)) that was wrong too... Thanks!