What happens to capacitors in an AC circuit?

In an AC circuit, capacitors continuously charge and discharge. This is due to the alternating nature of the current, which changes direction periodically. As the voltage across the capacitor increases, it stores energy in the form of an electric field. Once the voltage reaches its peak and begins to decrease, the stored energy is released back into the circuit. This process happens in sync with the AC waveform, allowing the capacitor to respond dynamically to the changing voltage.

This behavior is essential in various applications, such as filtering and timing circuits, where capacitors contribute to creating phase shifts and controlling the flow of alternating current. Unlike in a DC circuit, where a capacitor eventually reaches a point of full charge and maintains a static state, in an AC circuit, the continuous variation in voltage keeps the charging and discharging process ongoing.

The other options don't accurately describe a capacitor's behavior in an AC circuit. They either imply that the capacitor stops interacting with the current or block current altogether, which contradicts the fundamental properties of a capacitor's operation in an AC environment.