What term describes the opposition to the flow of current in an AC circuit?

Impedance is the comprehensive term that quantifies the total opposition to the flow of alternating current (AC) in a circuit. It combines both resistance and reactance. Resistance is the opposition to current due to heating, while reactance arises from the circuit's inductance and capacitance, affecting how current flows at different frequencies.

In AC circuits, impedance is measured in ohms and is represented as a complex number, capturing both the resistive and reactive components. This is essential because, unlike direct current (DC) circuits, AC circuits experience changes in current and voltage direction, leading to phase differences that must be accounted for. Therefore, understanding impedance is crucial for evaluating how AC circuits behave under different loading and frequency conditions.

Resistance, reactance, and conductance each describe components of electrical behavior, but none alone can fully encompass the unique characteristics of AC circuit opposition that impedance provides.