Resistance and impedance are commonly quantified and expressed in what unit?

Resistance and impedance are both critical concepts in electrical engineering and are fundamentally related to how electrical circuits behave. They are represented in the same unit, known as "Ohms."

Resistance specifically refers to the opposition to direct current (DC) electrical flow, while impedance extends this concept to alternating current (AC) circuits, where it accounts not only for resistance but also for reactance, which is the opposition to change in current due to capacitors and inductors. Both resistance and impedance measure how much a circuit will resist electrical flow, and therefore they share the same unit of measurement.

The other units listed serve distinct purposes in electrical engineering: volts measure electric potential, amperes quantify the flow of electric current, and watts express electrical power. While these units are integral to understanding electrical systems, they do not describe resistance or impedance, which specifically necessitates the use of Ohms.