The resistance provided by an inductor in an AC circuit is called which?

• A. Capacitive Reactance
• B. Resistance
• C. Inductive Reactance
• D. Impedance

Answer: (C)

In AC circuits, an inductor opposes changes in current not as real resistance, but through inductive reactance—the reactive part of its opposition to current. This inductive reactance increases with frequency and is given by X_L = 2πfL, where f is frequency and L is inductance. That means the inductor’s opposition grows as the signal changes faster, and the voltage across the inductor leads the current by 90 degrees. If the circuit is purely inductive, the total opposition is purely reactive (impedance is jX_L). The term capacitive reactance would describe a capacitor’s opposition, not an inductor, and resistance refers to the real power-dissipating part, which ideal inductors don’t have. Impedance is the total opposition combining resistance and reactance, so it’s broader than the specific effect of the inductor.