1. The problem statement, all variables and given/known data Consider three charges arranged as shown. What is the magnitude of the electric field strength at a point 2.7 cm to the left of the middle charge? The value of the Coulomb constant is 8.98755 × 109 N · m2/C2 . Answer in units of N/C. 2. Relevant equations I'm truly lost. I've been looking over some other places, trying to put things together, but nothing is becoming clear to me... How do the positive and negative charges affect each other? For example if I have 2 equal positive charges, the electric field should be 0 right? How do I determine it if it is 1 positive and 1 negative charge? (Both the same value -1 and +1) 3. The attempt at a solution I was looking at some similar problems. E1 = 8.98755e9 x 5.6e-6 / .064^2 = 1.228766602e7. I got that distance by finding the total distance between the point 2.7 cm to the left. So 3.7 + 2.7 = 6.4. That could be very wrong, I'm not sure. E2 = 8.98755e9 x 3.2e-6 / .047^2 = 1.301953825e7 E3 = 8.98755e9 x -1.8e-6 / .017^2 = -5.597782007 Then i just decided to add all three of those together... As I said I'm really lost, and I'm quite sure none of what I did is correct. Any help? Edit : Sorry... I inserted a picture to show the problem.