What is electrical impedance?

Electrical impedance is defined as the total opposition to the flow of alternating current (AC) in a circuit. It is a complex quantity that combines both resistance and reactance. While resistance is the opposition encountered in both AC and direct current (DC) circuits, reactance arises specifically in AC systems due to the capacitance and inductance in the circuit components. Impedance is measured in ohms and can be expressed as a combination of resistance (the real part) and reactance (the imaginary part).

In an AC circuit, the behavior of the current and voltage can vary significantly compared to a DC circuit, meaning that incorporating both resistance and reactance allows for a more complete understanding of how electrical energy flows in AC systems. Therefore, the classification of impedance as the total opposition to alternating current encompasses all factors affecting current flow in these types of circuits.