What does reactance refer to in an AC circuit?

Reactance refers specifically to the opposition to current flow in an alternating current (AC) circuit that arises from either inductance or capacitance. Unlike resistance, which dissipates energy in the form of heat in resistive components, reactance is concerned with how inductors and capacitors affect the AC circuit.

Inductive reactance occurs when the current tries to change direction, and the inductor resists this change due to its stored magnetic field—this is why inductors oppose changes in current. In contrast, capacitive reactance relates to how capacitors resist changes in voltage, as they store energy in an electric field.

In essence, reactance is a critical concept in AC circuit analysis because it helps in understanding how circuits behave under alternating currents, where both inductive and capacitive elements come into play. This distinguishes it from resistance and highlights its unique role in defining how AC circuits operate.