# Electrical resistivity and conductivity

Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current. Resistivity is commonly represented by the Greek letter ρ (rho). The SI unit of electrical resistivity is the ohm-meter (Ω⋅m).[1][2][3] For example, if a 1 m3 solid cube of material has sheet contacts on two opposite faces, and the resistance between these contacts is 1 Ω, then the resistivity of the material is 1 Ωm.

Resistivity
Common symbols
ρ
SI unitohm meter (Ω⋅m)
In SI base unitskg⋅m3⋅s−3⋅A−2
Derivations from
other quantities
${\displaystyle \rho =R{\frac {A}{\ell }}}$
Dimension${\displaystyle {\mathsf {M}}{\mathsf {L}}^{3}{\mathsf {T}}^{-3}{\mathsf {I}}^{-2}}$
Conductivity
Common symbols
σ, κ, γ
SI unitsiemens per metre (S/m)
In SI base unitskg−1⋅m−3⋅s3⋅A2
Derivations from
other quantities
${\displaystyle \sigma ={\frac {1}{\rho }}}$
Dimension${\displaystyle {\mathsf {M}}^{-1}{\mathsf {L}}^{-3}{\mathsf {T}}^{3}{\mathsf {I}}^{2}}$

Electrical conductivity or specific conductance is the reciprocal of electrical resistivity. It represents a material's ability to conduct electric current. It is commonly signified by the Greek letter σ (sigma), but κ (kappa) (especially in electrical engineering) and γ (gamma) are sometimes used. The SI unit of electrical conductivity is siemens per metre (S/m).