# conductance

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## conductance

the ability of a system to conduct electricity, measured by the ratio of the current flowing through the system to the potential difference across it; the reciprocal of resistance. It is measured in reciprocal ohms, mhos, or siemens.

## Conductance

The real part of the admittance of an alternating-current circuit. The admittance *Y* of an alternating-current circuit is a complex number given by Eq. (1). (1) The real part *G* is the conductance. The units of conductance, like those of admittance, are called siemens or mhos. Conductance is a positive quantity. The conductance of a resistor *R* is given by Eq. (2). (2)

In general the conductance of a circuit may depend on the capacitors and inductors in the circuit as well as on the resistors. For example, the circuit in the illustration has impedance at frequency &ohgr; given by Eq. (3) and admittance given by Eq. (4), so that the conductance, given by

(3)

(4)

(5)

Eq. (5), depends on the inductance *L*as well as the resistance

*R*.

*See*Admittance, Electrical impedance

## conductance

[kən′dək·təns] (electricity)

The real part of the admittance of a circuit; when the impedance contains no reactance, as in a direct-current circuit, it is the reciprocal of resistance, and is thus a measure of the ability of the circuit to conduct electricity. Also known as electrical conductance. Designated G.

(fluid mechanics)

For a component of a vacuum system, the amount of a gas that flows through divided by the pressure difference across the component.

(thermodynamics)

## thermal conductance

The time rate of flow of heat through a unit area of material from one of the faces of the material to the other, for a unit temperature difference between the two faces, under steady-state conditions.