1. The problem statement, all variables and given/known data Hello. I just need someone to check if I'm approaching the problem correctly (the steps I've taken are given below). I drew a quick sketch of the circuit here: http://i.imgur.com/mClttXn.png?1 In the problem, I am given the capacitances of A, B, and C. I am also given the voltage across capacitor B. My goal is to find the voltage of the battery. 2. Relevant equations Equivalent capacitance (series) = (cap1*cap2)/(cap2+cap1) Equivalent capacitance (parallel) = cap1 + cap2 + ... + capn Voltage = Q/C Total voltage (series) = V1 + V2 Charge = CV 3. The attempt at a solution Here are the steps I would take to find the voltage of the battery: I first find the equivalent capacitance across A and B, the two caps in parallel. Since capacitors in parallel have equal voltages, the voltage across the combined capacitor is the same as the one across capacitor B (let's pretend it was 9V. So the voltage across the combined cap is 9V). Now, I have the combined cap in series with capacitor C. Since the voltage across the battery is the sum of the voltages of the combined cap and cap C (please correct me if I'm wrong here), I need to find the voltage across C. To do this, I'll need the charge on C. Since the two caps are in series, I can find the charge Q of cap C by finding the charge Q on the combined cap (since the two charges should be equal). Once I find Q, I just divide that by the capacitance of C to obtain the voltage across C. The voltage of the battery = voltage across combined cap + voltage across C. Am I doing this correctly?