Inductor Guide

# Basic Facts about Inductors [Lesson 1] Overview of inductors - "How do inductors work?"

An inductor is a passive electronic component which is capable of storing electrical energy in the form of magnetic energy. Basically, it uses a conductor that is wound into a coil, and when electricity flows into the coil from the left to the right, this will generate a magnetic field in the clockwise direction.

Presented below is the equation that represents the inductance of an inductor. The more turns with which the conductor is wound around the core, the stronger the magnetic field that is generated. A strong magnetic field is also generated by increasing the cross-sectional area of the inductor or by changing the core of the inductor.

Let's now assume that an AC current is flowing through the inductor. "AC" (alternating current) refers to a current whose level and direction change cyclically over time. When current is about to flow to the inductor, the magnetic field generated by that current cuts across the other windings, giving rise to an induced voltage and thus preventing any changes in the current level. If the current is about to rise suddenly, an electromotive force is generated in the opposite direction to the current--that is, in the direction in which the current is reduced--thus preventing any increase in the current. Conversely, if the current is about to drop, an electromotive force is generated in the direction in which the current is increased.

These effects of the induced voltage are produced even when the direction in which the current is flowing is reversed. Before overcoming the induced voltage that is attempting to block the current, the direction of the current is reversed so that there is no flow of current.

The current level remains unchanged when DC (direct current) flows to the inductor so no induced voltage is produced, and it is possible to consider that a shorted state results. In other words, the inductor is a component that allows DC, but not AC, to flow through it.