[Physics] When I connect two charged capacitors side by side, what will be the voltage across them

capacitanceelectricityelectrostaticshomework-and-exercises

Say, I have two charged capacitors, one 3mF and one 2mF. The voltage across them are 20V and 30V respectively. Now if I connect the two capacitors side by side as shown below, what will be the voltage across each capacitor?

     open -------||----------------||-----------open
             20V, 3mF            30V, 2mF

Best Answer

Charges on all plates for capacitors in series must be equal. Q=CV for each capacitor. If you look at the charge per plate before you connect them in series, both have the same charge. So, after you connect them, nothing will change (no charge will flow). Since the capacitance of each capacitor doesn't change either, they keep the same voltages.