What is the function of a capacitor in an electrical circuit?

A capacitor functions primarily to store and release electrical energy within a circuit. It achieves this by accumulating electric charge on its plates when connected to a voltage source. When the circuit requires energy, the capacitor can discharge this stored energy back into the circuit. This ability to store energy and then release it plays a crucial role in smoothing out voltage fluctuations in power supplies, positioning it as a key component in various electrical applications including timing circuits, filters, and energy storage systems.

The other options are based on different devices or principles. For instance, stopping current flow is more characteristic of switches or circuit breakers rather than capacitors. Regulating voltage levels is typically handled by voltage regulators, while providing power directly to devices is a function associated with power sources like batteries or generators. Each of these components has its distinct role, highlighting the specific and vital function that capacitors serve in electrical circuits.