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 J to the electric field strength E:
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 rank2 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}) and CGSE units of inverse second (s^{–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.
Contents 
The degree of doping in solid state semiconductors makes a large difference in conductivity. More doping leads to higher conductivity. The conductivity of a solution of water is highly dependent on its concentration of dissolved salts, and sometimes other chemical species that ionize in the solution. Electrical conductivity of water samples is used as an indicator of how saltfree, ionfree, or impurityfree the sample is; the purer the water, the lower the conductivity (the higher the resistivity). Conductivity measurements in water are often reported as specific conductance, which is the conductivity of the water at 25 °C.
Material  Electrical Conductivity
(S·m^{1}) 
Notes 

Silver  63.0 × 10^{6}  Best electrical conductor of any known metal 
Copper  59.6 × 10^{6}  Commonly used in electrical wire applications due to very good conductivity and price compared to silver. 
Annealed Copper  58.0 × 10^{6}  Referred to as 100% IACS or International Annealed Copper Standard. The unit for expressing the conductivity of nonmagnetic materials by testing using the eddycurrent method. Generally used for temper and alloy verification of Aluminium. 
Gold  45.2 × 10^{6}  Gold is commonly used in electrical contacts because it does not easily corrode. 
Aluminium  37.8 × 10^{6}  Commonly used for High Voltage Mains electricity distribution cables^{[citation needed]} 
Sea water  4.8  Corresponds to an average salinity of 35 g/kg at 20 °C.^{[1]} 
Drinking water  0.0005 to 0.05  This value range is typical of high quality drinking water and not an indicator of water quality 
Deionized water  5.5 × 10^{6}  Conductivity is lowest with monoatomic gases present; changes to 1.2 × 10^{4} upon complete degassing, or to 7.5 × 10^{5} upon equilibration to the atmosphere due to dissolved CO_{2} ^{[2]} 
Jet A1 Kerosene  50 to 450 × 10^{12}  ^{[3]} 
nhexane  100 × 10^{12}  
Air  0.3 to 0.8 × 10^{14}  ^{[4]} 
To analyse the conductivity of materials exposed to alternating electric fields, it is necessary to treat conductivity as a complex number (or as a matrix of complex numbers, in the case of anisotropic materials mentioned above) called the admittivity. This method is used in applications such as electrical impedance tomography, a type of industrial and medical imaging. Admittivity is the sum of a real component called the conductivity and an imaginary component called the susceptivity.
An alternative description of the response to alternating currents uses a real (but frequencydependent) conductivity, along with a real permittivity. The larger the conductivity is, the more quickly the alternatingcurrent signal is absorbed by the material (i.e., the more opaque the material is). For details, see Mathematical descriptions of opacity.
Electrical conductivity is strongly dependent on temperature. In metals, electrical conductivity decreases with increasing temperature, whereas in semiconductors, electrical conductivity increases with increasing temperature. Over a limited temperature range, the electrical conductivity can be approximated as being directly proportional to temperature. To compare electrical conductivity measurements at different temperatures, they must be standardized to a common temperature. This dependence is often expressed as a slope in the conductivityvstemperature graph, which can be written as:
where
The temperature compensation slope for most naturally occurring waters is about 2 %/°C, however it can range between (1 to 3) %/°C. This slope is influenced by the geochemistry, and can be easily determined in a laboratory.
At extremely low temperatures (not far from absolute zero), a few materials have been found to exhibit very high electrical conductivity in a phenomenon called superconductivity.
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 J to the electric field strength E:
It is also possible to have materials in which the conductivity is anisotropic, different for currents travelling in different directions through the material. In this case σ is a 3×3 matrix (or more technically a rank2 tensor), which is generally symmetric.
Conductivity is the reciprocal (inverse) of electrical resistivity, $\backslash rho$, and has the SI units of siemens per metre (S·m^{1}) and CGSE units of inverse second (s^{–1}):
Electrical conductivity is commonly represented by the Greek letter σ, but κ (esp. in electrical engineering) or γ are also occasionally used.
An EC meter is normally used to measure conductivity in a solution.
Contents 
The degree of doping in semiconductors makes a large difference in conductivity. To a point, more doping leads to higher conductivity. The conductivity of a solution of water is highly dependent on its concentration of dissolved salts, and other chemical species that ionize in the solution. Electrical conductivity of water samples is used as an indicator of how saltfree, ionfree, or impurityfree the sample is; the purer the water, the lower the conductivity (the higher the resistivity). Conductivity measurements in water are often reported as specific conductance, the conductivity of the water at 25 °C.
Material  Electrical Conductivity
(S·m^{1})  Notes 

Silver  6.30 × 10^{7}  Best electrical conductor of any known metal 
Copper  5.69 × 10^{7}  Commonly used in electrical wire applications due to very good conductivity and price compared to silver. 
Annealed Copper  5.80 × 10^{7}  Referred to as 100% IACS or International Annealed Copper Standard. The unit for expressing the conductivity of nonmagnetic materials by testing using the eddycurrent method. Generally used for temper and alloy verification of aluminium. 
Gold  4.52 × 10^{7}  Gold is commonly used in electrical contacts because it does not easily corrode. 
Aluminium  3.5 × 10^{7}  Commonly used for high voltage electricity distribution cables^{[citation needed]} 
Sea water  4.8  Corresponds to an average salinity of 35 g/kg at 20 °C.^{[1]} 
Drinking water  0.0005 to 0.05  This value range is typical of high quality drinking water and not an indicator of water quality 
Deionized water  5.5 × 10^{6}  Conductivity is lowest with monoatomic gases present; changes to 1.2 × 10^{4} upon complete degassing, or to 7.5 × 10^{5} upon equilibration to the atmosphere due to dissolved CO_{2} ^{[2]} 
Jet A1 Kerosene  50 to 450 × 10^{12}  ^{[3]} 
nhexane  100 × 10^{12}  
Air  0.3 to 0.8 × 10^{14}  ^{[4]} 
To analyse the conductivity of materials exposed to alternating electric fields, it is necessary to treat conductivity as a complex number ( or as a matrix of complex numbers, in the case of anisotropic materials ) called the admittivity. This method is used in applications such as electrical impedance tomography, a type of industrial and medical imaging. Admittivity is the sum of a real component called the conductivity and an imaginary component called the susceptivity.
An alternative description of the response to alternating currents uses a real (but frequencydependent) conductivity, along with a real permittivity. The larger the conductivity is, the more quickly the alternatingcurrent signal is absorbed by the material (i.e., the more opaque the material is). For details, see Mathematical descriptions of opacity.
Electrical conductivity is strongly dependent on temperature. In metals, electrical conductivity decreases with increasing temperature, whereas in semiconductors, electrical conductivity increases with increasing temperature. Over a limited temperature range, the electrical conductivity is approximately directly proportional to temperature. To compare electrical conductivity measurements at different temperatures, they must be standardized to a common temperature. This dependence is often expressed as a slope in the conductivityvstemperature graph, which can be written as:
where
The temperature compensation slope for most naturally occurring waters is about 2 %/°C, however it can range between (1 to 3) %/°C. This slope is influenced by the geochemistry, and can be easily determined in a laboratory.
At extremely low temperatures (not far from absolute zero), a few materials have been found to exhibit very high electrical conductivity in a phenomenon called superconductivity.
Electrical conductivity is a measure of how well a material accommodates the transport of electric charge. Its SI derived unit is the siemens per metre, (A^{2}s^{3}m^{3}kg^{1}) (named after Werner von Siemens) or, more simply, Sm^{1}. It is the ratio of the current density to the electric field strength or, in more practical terms, is equivalent to the electrical conductance measured between opposite faces of a 1metre cube of the material under test.
Elecrical conductance is an electrical phenomenon where a material contains movable particles with electric charge (such as electrons), which can carry electricity. When a difference of electrical potential is placed across a conductor, its movable charges flow, and an electric current appears.
A conductor such as a metal has high conductivity, and an insulator like glass or a vacuum has low conductivity. A semiconductor has a conductivity that varies widely under different conditions.
Electrical conductivity is the reciprocal (or inverse) of electrical resistivity.
