How is "reactance" defined in electric circuits?

Reactance is defined as the opposition created by inductors and capacitors in an alternating current (AC) circuit. Unlike resistance, which opposes the flow of electric current from resistors, reactance varies with the frequency of the applied AC signal. Inductors generate reactance due to their property of opposing changes in current, while capacitors oppose changes in voltage. This reaction to AC signals can cause phase shifts between the voltage and current in the circuit, distinguishing reactance from simple resistance, which is constant regardless of frequency.

Understanding that reactance is specific to inductors and capacitors is crucial because it highlights the frequency-dependent behavior of these components, differing from resistive elements that provide a consistent opposition. This distinction is fundamental in the analysis of AC circuits and their behavior in various applications.