Inductor

Meet the inductor, SparkVille’s patient keeper of current. It is a wire wound into a coil. Current through the winding creates a magnetic field that stores energy. When the current changes, the coil produces a voltage that opposes that change. It slows sudden changes in current; it does not block steady DC current. Our picture shows an air-core coil; other inductors have a magnetic core.

Inductance is written L and measured in henries (H). This simple two-lead coil has no + or −, so either connection direction works. Interrupting its current can produce a voltage spike as the magnetic field releases its energy.

In the town’s radio, an inductor teams up with a capacitor to help select a station. Together they tune in the festival broadcast, so Sparkie can hear when the music starts.