PCB Currents: How They Flow, How They React

6. Reactive Circuits: Inductors and Inductance

6.1. The Nature of Inductance

Inductance is not an intuitive concept. It is often one of the hardest things in electronics for people to understand. But once you “get it,” it turns out that inductance is pretty straightforward, particularly in the way it contrasts with resistance and capacitance.

Start with the idea that if you pass a current through a wire, a magnetic field is generated around the wire (Ampere’s Law). This is the fundamental principle behind a motor. The effect can be demonstrated several ways. Take a battery and momentarily short its two terminals with a wire that is placed close ...