My question is: A 3.00 uF and a 5.00 uF capacitor are connected in series across a 30.0 V battery. A 7.00 uF capacitor is then connected in parallel across the 3.00 uF capacitor. Determine the voltage across the 7.00 uF capacitor. Ok, there are two situations, one with the 7 capacitor and one without. Ok, so I guess I can find the equivalent capacitances by combining some of the capacitors. So for situation 1: 1/Cs=1/(3x10^-6F)+1/(5.00x10^-6F), (1/Cs)^-1=Cs Cs=1.88x10^-6F Ok now for situation 2: 1/Cs=1/(7.00x10^-6F+3.00x10^-6F)+1/(5.00x10^-6F) My Cs here is: 8.33x10^-6 F. Here's where I'm stuck: I think I can go, CV=CV+CV Or Ctotal x Vtotal= Ctotal x Vtotal +C at 7 x V at 7. Any ideas? Thanks.