1. The problem statement, all variables and given/known data The lines show equipotential contours in the plane of three point charges, Q1, Q2, and Q3. The positions of the charges are marked by dots. The values of the potentials are in kilovolts as indicated, e.g., +5 kV, −5 kV; the contour interval is 1 kV. The letters denote locations on the contours. For distances use the scale below the picture, to an appropriate accuracy. Select all the correct statements, e.g., AB. http://img100.imageshack.us/img100/2589/physicswe4.jpg [Broken] http://g.imageshack.us/img100/physicswe4.jpg/1/ [Broken] A) The electric field at g is zero. B) Charge Q2 is the largest negative charge. C) Q1 is a negative charge. D) The electric field at d is stronger than at b. E) Charge Q3 is the largest positive charge. F) The force on an electron at g points to the top of the page. 2. Relevant equations No equations necessary, theory only. 3. The attempt at a solution Last Answer: CE Last Answer: BCE Last Answer: BCEF Last Answer: ABCEF Last Answer: ABCE Last Answer: ACE Last Answer: ACEF I just don't know the theory behind this, I've been tried, failed, and I don't understand. If anyone can explain the concepts and what the right answer is, I'd really appreciate it.