# Capacitor in AC circuit

ay2k
Hello.
When a capacitor is connected in a circuit with an ac supply, a current flows in the circuit. fine. The problem is, does a pd develops across that capacitor, and does it store energy. As in does it "Charge" up?

ay2k
oh sorry, this thread shouldn't have been here.
But still, anyone?

TVP45
Yes. No. Yes. No. Yes. No...

ay2k
ok now...comeon...:P

say it clearly, I am too dumb to understand your joke...

Yes or no?

TVP45
Yes, there will be an ac Voltage across the capacitor. Depending on the quality of the capacitor, the Voltage will lag the current by up to 90 degrees.

ay2k
so will it store energy?

since w=1/2 cv^2

Staff Emeritus
Gold Member
A capacitor does store energy, but it is stored in the electric field between the plates. As the charge builds up on the two plates, a potential difference, and hence an electric field, is generated between the plates. To put more charge on the plates an emf must do work against this electric field and it is this work which is 'stored' as energy in the field.

Do you follow?

ay2k
ok so what about AC current which changes direction 50 times every second?
The direction of electric field has to change also...
So will it constantly cancel each other's effect or what?

Staff Emeritus