Reactive Loads

The current and voltage in AC circuits that contain inductors, capacitors, or both, behave much differently than in a purely resistive circuit. We cannot measure resistance directly in these circuits. We measure what's known as "reactance."

Inductors and capacitors react to current flow in ways that oppose, or impede, changes in the flow of current, but they do it in a different fashion than a pure resistor. Each device has its own characteristics which creates an impeding force.

Whenever there is an inductor, or coil, in a circuit, we call its impeding force to current flow "inductive reactance." For a circuit with a capacitor, the impeding force is called "capacitive reactance."

We treat both resistance and reactance as impedance, that is, any opposition to changes in the flow of current.