What does inductive reactance (XL) indicate in an AC circuit?

Inductive reactance (XL) is a fundamental concept in alternating current (AC) circuit theory that specifically refers to the opposition to current flow caused by inductors in the circuit. When current flows through an inductor, it generates a magnetic field, and changes in current create a back electromotive force (EMF) that opposes the current flow. This phenomenon is a result of Lenz's Law, which states that the direction of induced EMF will always oppose the change in current that created it.

Inductive reactance is measured in ohms and is frequency-dependent; it increases with the frequency of the AC signal. Therefore, it is crucial for understanding how inductors behave in AC circuits, especially when designing and analyzing circuits that include inductive components.

In contrast, the other options relate to different concepts within AC circuits. Resistance relates to direct opposition to current in both AC and DC circuits but does not specifically pertain to inductive reactance. The idea of current leading voltage is a phase relationship commonly associated with capacitive and inductive components. Instantaneous voltage refers to the voltage at a specific moment in time and does not define the characteristics of inductive reactance.