An inductor is a passive electrical device employed in electrical circuits for its property of inductance. An inductor can take many forms.
An inductor, sometimes called a coil or reactor, is a passive two-terminal electrical component that resists changes in electric current passing through it. It consists of a conductor such as wire, usually wound into a coil.
When a current flows through it, energy is stored temporarily in a magnetic field in the coil. When the current flowing through an inductor changes, the time-varying magnetic field induces a voltage in the conductor, according to Faraday’s law of electromagnetic induction that opposes the change in current that created it.
An inductor is characterized by its inductance, the ratio of the voltage to the rate of change of current that has units of henries. Many inductors have a magnetic core made of iron or ferrite inside the coil that serves to increase the magnetic field and thus the inductance. Along with capacitors and resisters, inductors are one of the three passive linear circuit elements that make up electric circuits.
Inductors are widely used in AC electronic equipment, particularly in radio equipment. They are used to block the flow of AC current while allowing DC to pass; inductors designed for this purpose are called chokes. They are used in electronic filters to separate signals of different frequencies, and in combination with capacitors to make tuned circuits, used to tune radio and television receivers.