Impedance in electrical engineering is measured in which units?

Impedance is a measure of the opposition that a circuit presents to the flow of alternating current (AC) and is quantified in ohms. This unit is derived from the work of Georg Simon Ohm, who established the relationship between voltage, current, and resistance in electrical circuits.

In the context of impedance, which encompasses both resistance and reactance (due to inductance and capacitance), the use of ohms provides a standardized way to express how much opposition a circuit provides to AC signals. Resistance is purely a measure of opposition to direct current (DC), while impedance extends the concept to AC, considering both the resistive and reactive components.

Using volts, amps, or watts would not accurately reflect the concept of impedance. Volts measure electrical potential, amps measure current flow, and watts represent power, all of which are related but distinct from the concept of how much a circuit resists AC flow, which is specifically what impedance describes.