# How to determine the steady state voltage across two capacitors in parallel

Say we have two capacitors C1 and C2, initially isolated from each other and each having an initial voltage Vc1 and Vc2 respectively, where Vc1>Vc2. When suddenly connected to each other in parallel, obviously C1 will discharge to C2 until their voltages meet at a steady state value. Assuming zero resistance between the two capacitors, what is the expression for this steady state voltage Vc in terms of Vc1 and Vc2? Is it just the average of Vc1 and Vc2?

• I think if you assume zero resistance, things get complicated. It's better to assume a very small resistance for the math to make sense – Simeon R Mar 28 at 6:24
• before you connect them there will small air gap between them that will ionize air and start conducting some charge. after you connect them you will have infiniti amp for 0s. how? i dont know. anyway all caps have resistance within them you cant have 0 resistance. bottom line its intresting question but doesnt apply to real life and i dont know the answer. but just wanted to share my thoughts – Hasan alattar Mar 28 at 6:37
• The charge is conserved. There is excess energy that gets radiated. – analogsystemsrf Mar 28 at 6:46
• @analogsystemsrf Thanks! had you come a little earlier I would have spared my friend the trouble (and myself the embarrassment)! – FartVader Mar 28 at 6:49

• If initial voltages are different, KVL is violated in $t=0$. There an impulsive ($\delta(t)$) current in $t = 0$. Charge is conserved, energy not. The energy before closing the switch is $>$ than the energy after closing the switch (except for equal initial voltages). – Dirceu Rodrigues Jr Mar 29 at 1:44