Define impedance in electrical circuits.

Impedance is defined as the total opposition to current flow in an alternating current (AC) circuit. It is a complex quantity that combines both resistance and reactance, as it accounts for not only the opposition due to resistive components but also the effects of inductance and capacitance, which are frequency-dependent. This total opposition is measured in ohms and is critical for understanding how AC circuits behave, especially in cases involving varying frequencies.

Understanding impedance is essential for designing and analyzing circuits that utilize AC power since voltage and current can be out of phase due to reactance. This concept becomes crucial in applications such as audio electronics and power distribution, where the phase relationship between voltage and current affects performance and efficiency.

The other choices address different electrical parameters. Voltage is a measure of electrical potential, maximum power output relates to how much power an electrical device can deliver, and energy consumption is about the rate at which energy is drawn by a circuit. None of these definitions relate to the comprehensive opposition to current flow that impedance represents in AC circuits.