# Capacitor in AC circuit

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?

## Answers and Replies

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oh sorry, this thread shouldnt have been here.
But still, anyone?

Yes. No. Yes. No. Yes. No....

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

say it clearly, im too dumb to understand your joke....

Yes or no?

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.

so will it store energy?

since w=1/2 cv^2

Hootenanny
Staff Emeritus
Science Advisor
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?

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?

Hootenanny
Staff Emeritus
Science Advisor
Gold Member
Here's a nice reference on http://www.physclips.unsw.edu.au/jw/AC.html#capacitors" [Broken].

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thankyou.
That was helpful.