Electrical conductivity or specific conductance is a measure of a material's ability to conduct an electric current. When an electrical potential difference is placed across a conductor, its movable charges flow, giving rise to an electric current. The conductivity σ is defined as the ratio of the current density to the electric field strength :
It is also possible to have materials in which the conductivity is anisotropic, in which case σ is a 3×3 matrix (or more technically a rank-2 tensor) which is generally symmetric.
Conductivity is the reciprocal (inverse) of electrical resistivity, ρ, and has the SI units of siemens per metre (S·m-1):
Electrical conductivity is commonly represented by the Greek letter σ, but κ (esp. in electrical engineering science) or γ are also occasionally used.
An EC meter is normally used to measure conductivity in a solution.