What is a capacitor used for in electrical circuits?

A capacitor is utilized in electrical circuits primarily to store electrical energy and release it as needed. This functionality is crucial in various applications, such as filtering, timing, and smoothing out voltage fluctuations in power supplies.

When electrical energy is applied to a capacitor, it accumulates charge on its plates, enabling it to temporarily store energy. This stored energy can then be released back into the circuit when required, helping to stabilize voltage levels and maintain a consistent power supply to other components. This behavior is particularly important in applications such as power factor correction, coupling and decoupling signals, and energy storage in power systems.

The other choices do not accurately describe the primary function of a capacitor. While current flow may be affected by the presence of capacitors in circuits, they do not boost current. Capacitors are not directly used for measuring voltage, and they do not function as a fuse, which is designed to protect circuits by breaking the connection when excessive current flows. Thus, this characteristic of capacitors, as energy storage devices, is essential for understanding their role in electrical circuits.