1. The problem statement, all variables and given/known data Capacitors C1 = 6.18 µF and C2 = 1.69 µF are charged as a parallel combination across a 250 V battery. The capacitors are disconnected from the battery and from each other. They are then connected positive plate to negative plate and negative plate to positive plate. Calculate the resulting charge on capacitor C1. Q1= charge on C1 when in parallel Q2= charge on C2 when in parallel. q1= charge on C1 when connected in series. q2= charge on C2 when connected in series. Qt= total charge 2. Relevant equations C=Q/ΔV 3. The attempt at a solution V1= q1/C1, V2= q2/C2, V1= V2, q2= q1*(C2/C1) q1+q2= Qtotal sub in q2 from above q1+q1*(C2/C1) = Qtotal Isolate q1 q1= Qt*(C1/(C1+C2)) Now I know how to get the answer, the problem is my understanding. In order to get the correct answer you must take Qt = Q1 - Q2, I can't understand why this is. I thought the total would be Q1+Q2 = Qt just like q1+q2=Qt If I can't understand it I can't move on.