A measure of resistance or impedance. 1 Ω = 1 V/A = 1 W/A2 Ohm is the unit of resistance
The ohm is defined as a resistance between two points of a conductor when a constant potential difference of 1 volt, applied to these points, produces in the conductor a current of 1 ampere, the conductor not being the seat of any electromotive force.
- V = volt
- A = ampere
- m = meter
- kg = kilogram
- s = second
- C = coulomb
- J = joule
- S = siemen
In many cases the resistance of a conductor in ohms is approximately constant within a certain range of voltages, temperatures, and other parameters; one speaks of linear resistors. In other cases resistance varies (e.g., thermistors).
Commonly used multiples and submultiples in electrical and electronic usage are the milliohm, ohm, kilohm, megohm, and gigaohm.
In alternating current circuits, electrical impedance is also measured in ohms.