How is electrical resistance measured?

Electrical resistance is measured in ohms. The ohm is the standard unit of measurement for resistance in electrical circuits. It quantifies how much a material opposes the flow of electric current. When a voltage (measured in volts) is applied across a resistor, the resistance determines how much current (measured in amperes) will flow through the circuit for that voltage.

Ohm’s Law, defined as V = IR (where V is voltage, I is current, and R is resistance), illustrates this relationship, showing that resistance can be calculated as the ratio of voltage to current. Hence, when current flows through a conductor, the inherent resistance of that material can be directly measured in ohms, making it the correct choice for how electrical resistance is quantified.

The other units mentioned relate to different aspects of electrical circuits: volts measure the potential difference, watts measure power, and amperes measure current flow. These do not pertain directly to the measurement of resistance itself.