Opposition to AC in an inductor — the specific term for an inductor’s frequency-dependent opposition to alternating current is what?

Introduction / Context:
While resistors oppose current independent of frequency (ideally), inductors and capacitors oppose AC in a frequency-dependent manner. Using precise terminology helps avoid confusion when calculating circuit behavior. This question asks for the name of an inductor’s AC opposition.

Given Data / Assumptions:

• Linear time-invariant circuit elements.
• Sinusoidal steady-state analysis at a single frequency f.
• Ideal inductor with reactance proportional to frequency.

Concept / Approach:
The inductor’s AC opposition is called inductive reactance, symbol X_L, given by X_L = 2 * pi * f * L (in ohms). “Impedance” Z is the vector sum of resistance and reactance (Z = R + jX). “Reluctance” is a magnetic circuit term for opposition to magnetic flux (analogous to resistance but in the magnetic domain). “Resistance” alone denotes the real (lossy) part, not the frequency-dependent imaginary part provided by the inductor.

Step-by-Step Solution:

Verification / Alternative check:
Phasor calculations: the inductor’s impedance is Z_L = jX_L = j * (2 * pi * f * L). The magnitude |Z_L| equals X_L, confirming that “reactance” is the proper term for the opposition’s magnitude.

Why Other Options Are Wrong:

• Impedance: Too general; includes both resistance and reactance.
• Reluctance: Wrong domain; magnetic circuits, not electrical AC circuits.
• Resistance: Real power-dissipative term, not the reactive opposition unique to inductors/capacitors.

Common Pitfalls:
Using “impedance” and “reactance” interchangeably. Remember: impedance is the complex total; reactance is the imaginary component (X_L or X_C).

Final Answer:
reactance is the correct term.