Determining Direction of Electric Field! :) 1. The problem statement, all variables and given/known data Calculate the electric field at one corner of a square 50 cm on a side if the other three corners are occupied by 250 x 10^-7 C charges. 2. Relevant equations E = (kQ)/(r^2) Where: E = Electric Field Intensity in (N/C) k = Electrostatics Constant (9 X 10^9 Nm^2/C^2) Q = Charge in (C) r = separation in (m) 3. The attempt at a solution Firstly, I calculated the E from one corner to each of the three charges: E1 = [(9 x 10^9 Nm^2/C^2)(250 x 10^7 C)]/(.50m)^2 = 9 x 10^5 N/C (Not Sure of Direction) E2 = [(9 x 10^9 Nm^2/C^2)(250 x 10^7 C)]/(.50m)^2 = 9 x 10^5 N/C (Not Sure of Direction) E3 = [(9 x 10^9 Nm^2/C^2)(250 x 10^7 C)]/(.71m)^2 = 4.5 x 10^5 N/C (Not Sure of Direction) (Note the change in r, as this is diagonal from the corner) I then added the E.s up: Etotal = E1 + E2 + E3 = (9 x 10^5 N/C) + (9 x 10^5 N/C) + (4.5 x 10^5 N/C) Because E1 + E2 are not on the same plane, I would have to use Pythagoras to add the two, and then add it to E3. So, Etotal = E1 + E2 + E3 = (9 x 10^5 N/C) + (9 x 10^5 N/C) + (4.5 x 10^5 N/C) = (1.3 x 10^6 N/C) + (4.5 x 10^5 N/C) = 1.8 X 10^6 N/C Okay, wait. When I typed it out here and did all the calculations, I got the right answer! That's weird, considering every other time I did it it was wrong. Anyway, I still have to determine the direction of the Electric Field. In my answer key, it says: [AWAY FROM CENTER], which I do not understand. Is it because I am dealing with all positive charges, so they all repel each other? I am simply terrible when it comes to determining direction, so please help!