What term is used to describe the total opposition to current flow in a circuit?

The term that describes the total opposition to current flow in a circuit is impedance. Impedance encompasses not only the pure resistance found in a circuit—where the opposition to current flow is constant—but also considers reactance, which arises in circuits with inductive or capacitive elements. Reactance varies with frequency, affecting how AC (alternating current) behaves differently compared to DC (direct current).

Understanding impedance is crucial in AC circuits as it informs how much current will flow for a given voltage, which is particularly important in designing efficient electrical systems. Impedance is typically represented as a complex number, incorporating the phase relationship between voltage and current, making it essential for analyzing and designing circuits involving varying frequencies.

Resistance, voltage, and capacitance do play important roles in electrical circuits, but they do not capture the complete picture of opposition to current flow that impedance entails, especially in circuits that are not limited to resistive loads.