I have a few general questions which I need some clarification on. 1. What is really the relationship between potentials and test charges? I know how they relate to capacitance, but not really to each other. For example would a charge of 5mC be drawn to a potential of -7V or 7V? 2. I know that two equal charges, like +8 and +8, will cancel each other, but I want to clarify if +6 and -6 cancel as well. I am thinking that they do because they are still of equal force and are in opposite directions, but I just want to make sure. 3. If you have a line with +3 and -3 and you place a charge of -7 between them do they have the same force on the -7 charge, but are both in the same direction because one attracts and one repels? So, for example, if the force from the +3 on the -7 was 2 N, would the combined forces be 4 N to the direction of the +3?