What is the impedance in an AC circuit?

Impedance in an AC circuit is defined as the total opposition to current flow. It encompasses not only the resistance, which is the opposition to direct current, but also the reactance, which relates to how the circuit responds to changes in current and voltage over time due to inductors and capacitors.

In an AC circuit, impedance is a complex quantity that includes both real and imaginary components. The real part is the resistance, and the imaginary part is the reactance. This total opposition is crucial because it determines how much current will flow when a voltage is applied, integrating both resistance and the effects of inductance and capacitance.

This understanding is fundamental for analyzing and designing AC circuits, as it influences factors such as power factor, voltage drops, and overall circuit efficiency. The other choices, such as the total voltage supplied, the difference in voltage between two points, and energy loss, pertain to different aspects of electrical circuits rather than the comprehensive concept of impedance.