1. The problem statement, all variables and given/known data Two metal objects have net charges of +70pC and -70pC, which result in a 20V potential difference between them. a.) What is the capacitance of the system? b.)If the charges are changed to +200pC and -200pC, what does the capacitance become? 2. Relevant equations Q=CV [itex]C=\epsilon A/d[/itex] 3. The attempt at a solution a.) Q=CV C=Q/V = 70e-12 / 20 = 3.5pF b.) I know the capacitance only relies on the area and the distance between the plates. But that is not obvious from Q=CV. Why can't this equation be used to find the answer by substituting in the 200pF for the charge and 20V? It's not obvious from these equations why and the book's descriptions absolutely suck.