# capacitor in ac circuits

#### harikanaidu

Joined Nov 28, 2014
77
Hi, can anyone explain me how a capacitor stores charge when used in ac circuits

#### harikanaidu

Joined Nov 28, 2014
77
Will that shows they do not hold any charge???

#### harikanaidu

Joined Nov 28, 2014
77
Generally, in circuits with DC source ,when the charge flow through the capacitor, when it reaches the supply voltage an opposing current will restrict further flow of charge...Thus it holds the charge....until it is applied to the load...but how it is possible in case of AC???

#### Alec_t

Joined Sep 17, 2013
13,776
The cap charges and discharges with one polarity during during one AC half cycle, then charges and discharges with the opposite polarity during the next half cycle. The average charge over one complete cycle will be zero, but the instantaneous or RMS charge will not.

#### harikanaidu

Joined Nov 28, 2014
77
Thank you

#### WBahn

Joined Mar 31, 2012
29,153
Generally, in circuits with DC source ,when the charge flow through the capacitor, when it reaches the supply voltage an opposing current will restrict further flow of charge...Thus it holds the charge....until it is applied to the load...but how it is possible in case of AC???
Where does this "opposing current" come from?

In the DC case, when the capacitor reaches the it's final voltage, then there is NO current flowing at all. It is the VOLTAGE on the capacitor that inhibits further flow of charge.

#### hp1729

Joined Nov 23, 2015
2,304
Hi, can anyone explain me how a capacitor stores charge when used in ac circuits
Yes, if the current is stopped when the voltage drops to zero there is no charge on the capacitor. If current is dropped when the voltage is at it's peak then the capacitor retains its charge, or will discharge slowly, as R x C, right? If in charging the capacitor is large enough R x C exceeds the 50 or 60 Hz cycle time the capacitor retains a charge. The magic is all about R x C.