1. The problem statement, all variables and given/known data A 1.00 micro-F capacitor charged to 50.0 V and a 2.00 micro-F capacitor charged to 20.0 V are connected, with the positive plate of each connected to the negative plate of the other. What is the final charge on the 1.00 micro-F capacitor? 2. Relevant equations Q = CV 3. The attempt at a solution Let a subscript of 1 denote the 1.00 micro-F capacitor, and a subscript of 2 denote the other. Intially: Q1 = C1V1 = 50 micro-C Q2 = C2V2 = 40 micro-C When the two capacitors are connected together, the first one has charge Q1' and the second has charge Q2' with: Q1' + Q2' = 50 - 40 = 10 micro-C The total potential drop around the loop must be zero, so we have V1' = V2' so Q1'/C1 = Q2'/C2 Then when I solve for Q1', I get 3.3 micro-C, which is wrong. The correct answer according to the textbook is 45 micro-C.