1. The problem statement, all variables and given/known data A, B, C and D are corners of a square in empty space, sides 12 micrometres, charges +5nC and -5nC are placed at corners A and B respectively. What is the change in the electric potential from D to C? (take care with sign) A third charge of -2nC is initially at D then moved to C, what is the change in the potential energy of the system? (take care with sign) 2. Relevant equations not sure, something linking distance and charge 3. The attempt at a solution if the charges are in space, there is no conduction of charge so at D and C wouldn't you expect there to be no electric potential?