[SOLVED] Potential Change in a Circuit Diagram 1. The problem statement, all variables and given/known data If the potential at point P is 400 V, what is the potential at point Q? 2. Relevant equations Ohm's Law: deltaV=iR Probably the fact that the sum of changes in potential in a loop of any circuit must be zero. 3. The attempt at a solution Not real sure on this problem. I tried this: 150V - 2.0i - 3.0i - 50V = 0V and found i to be 20A. I'm kind of puzzled and can't seem to relate the material in the textbook to this problem. Where does the 400V potential come into play? Thanks for your help!