Inductors

When there is a current in the inductor, a magnetic field is created. Any change in current causes the magnetic field to change, this in turn induces a voltage across the inductor that opposes the original change in current. The polarity of the induced magnetic field opposes the change in current.

A length of wire turned into a coil works as an inductor.

Inductance (L)

For an ideal inductor:

Here:

• - voltage difference across the inductor
• - current through the inductor

Energy stored

Suppose current across an inductor rises from to during a time period of seconds.