ऊर्जा की एक इकाई जो किसी चालक के दो बिन्दुओं के बीच के विद्युत्-प्रभाव के अंतर के बराबर होती है।

A unit of potential equal to the potential difference between two points on a conductor carrying a current of 1 ampere when the power dissipated between the two points is 1 watt. Equivalent to the potential difference across a resistance of 1 ohm when 1 ampere of current flows through it.