# Resolution 2 of the 41st CIPM (1946)

## Definitions of electric units

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**A) Definitions of the mechanical units which enter the definitions of electric units:**

**Unit of force**- The unit of force [in the MKS (metre, kilogram, second) system] is the force which gives to a mass of1 kilogram an acceleration of1 metre per second, per second.**Joule**(unit of energy or work) - The joule is the work done when the point of application of1 MKS unit of force [newton] moves a distance of1 metre in the direction of the force.**Watt**(unit of power) - The watt is the power which in one second gives rise to energy of1 joule.

**B) Definitions of electric units:**

The Comité International des Poids et Mesures (CIPM) accepts the following propositions which define the theoretical value of the electric units:

**Ampere**(unit of electric current) - The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed1 metre apart in vacuum, would produce between these conductors a force equal to2 ´ 10 MKS unit of force [newton] per metre of length.^{-7}**Volt**(unit of potential difference and of electromotive force) - The volt is the potential difference between two points of a conducting wire carrying a constant current of1 ampere, when the power dissipated between these points is equal to1 watt. **Ohm**(unit of electric resistance) - The ohm is the electric resistance between two points of a conductor when a constant potential difference of1 volt, applied to these points, produces in the conductor a current of1 ampere, the conductor not being the seat of any electromotive force.**Coulomb**(unit of quantity of electricity) - The coulomb is the quantity of electricity carried in1 second by a current of1 ampere. **Farad**(unit of capacitance) - The farad is the capacitance of a capacitor between the plates of which there appears a potential difference of1 volt when it is charged by a quantity of electricity of1 coulomb. **Henry**(unit of electric inductance) - The henry is the inductance of a closed circuit in which an electromotive force of1 volt is produced when the electric current in the circuit varies uniformly at the rate of1 ampere per second.**Weber**(unit of magnetic flux) - The weber is the magnetic flux which, linking a circuit of one turn, would produce in it an electromotive force of1 volt if it were reduced to zero at a uniform rate in1 second.