Tag Electrical conductivity

Electrical conductivity is a parameter used to describe the ease of charge flow in a substance. In the formula, conductivity is represented by the Greek letter σ.

The standard unit of conductivity σ is Siemens/meter (abbreviated as S/m), which is the reciprocal of resistivity ρ, that is, σ=1/ρ.

The conductance of an object is 1 S when a current of 1 ampere (1 A) is passed through its cross-section and a voltage of 1 volt (1 V) is present. Siemens is actually equivalent to 1 Amp/Volt. If G is conductance (in Siemens), I is current (in amperes), and U is voltage (in volts), then:

G = I/U

The conductivity σ can be calculated by the conductance G, the cross-sectional area A of the conductor, and the length l of the conductor:

σ = Gl/A

Typically, the current in such a DC circuit is proportional to the conductance when the voltage is held constant. If the conductance is doubled, the current is also doubled; if the conductance is reduced to 1/10 of its original value, the current also becomes 1/10 of its original value.

This rule also applies to many low-frequency AC systems, such as household circuits. In some AC circuits, especially high-frequency circuits, the situation becomes very complicated because components in these systems store and release energy.