What is the primary function of a capacitor in a circuit?

The primary function of a capacitor in a circuit is to store and release electrical energy. Capacitors are passive electronic components that can temporarily hold an electrical charge. When voltage is applied across a capacitor, it stores electrical energy in an electric field created between its plates. This stored energy can then be released back into the circuit when needed, allowing the capacitor to smooth out variations in voltage, filter signals, or provide bursts of energy when the circuit requires it.

In comparison, the other functions attributed to the incorrect options do not align with the primary purpose of a capacitor. While converting AC to DC is a function commonly associated with diodes and rectifiers, limiting current flow is typically the role of resistors. Measuring voltage is performed by voltmeters, not capacitors. Thus, the unique ability of capacitors to store energy distinguishes their role in electrical circuits.