What is the primary function of an inductor in a circuit?

The primary function of an inductor in a circuit is to store energy in a magnetic field. Inductors achieve this by opposing changes in current. When current passes through an inductor, it creates a magnetic field around it. If the current changes, the magnetic field will either expand or collapse, inducing a voltage that opposes that change in current according to Lenz's Law. This property allows inductors to effectively store energy temporarily and is key in applications such as filters, oscillators, and energy storage in power supplies.

In the context of other options, converting AC to DC is primarily the function of rectifiers, not inductors. Amplifying current is typically done by transistors or operational amplifiers. Reducing electromagnetic interference is more associated with capacitors or shielding techniques rather than the inherent properties of inductors. Therefore, the storage of energy in a magnetic field is the most relevant and accurate description of an inductor's primary role in a circuit.