{"id":710,"date":"2007-05-25T16:21:52","date_gmt":"2007-05-25T21:21:52","guid":{"rendered":"http:\/\/softbeam.net\/hobby\/?p=710"},"modified":"2007-05-25T16:21:52","modified_gmt":"2007-05-25T21:21:52","slug":"electrical-conductivity","status":"publish","type":"post","link":"https:\/\/softbeam.net\/hobby\/?p=710","title":{"rendered":"electrical conductivity"},"content":{"rendered":"

Electrical conductivity<\/strong> or specific conductivity<\/strong> is a measure of a material’s ability to conduct<\/a> an electric current<\/a>. When an electrical potential difference<\/a> is placed across a conductor, its movable charges flow, giving rise to an electric current. The conductivity \u03c3 is defined as the ratio of the current density<\/a> \"\\mathbf{J}\" to the electric field<\/a> strength \"\\mathbf{E}\":<\/p>\n

\n
\"\\mathbf{J}.<\/dd>\n<\/dl>\n

It is also possible to have materials in which the conductivity is anisotropic<\/a>, in which case \u03c3 is a 3\u00d73 matrix<\/a> (or more technically a rank-2 tensor<\/a>) which is generally symmetric<\/a>.<\/p>\n

Conductivity is the reciprocal<\/a> (inverse<\/a>) of electrical resistivity<\/a> and has the SI units of siemens<\/a> per metre<\/a> (S\u00b7m-1<\/sup>) i.e. if the electrical conductance between opposite faces of a 1-metre cube of material is 1 siemens then the material’s electrical conductivity is 1 siemens per metre. Electrical conductivity is commonly represented by the Greek letter<\/a> \u03c3<\/a>, but \u03ba<\/a> or \u03b3<\/a> are also occasionally used.<\/p>\n

Also:<\/p>\n

For a device with electrical resistance<\/a> R<\/em>, the conductance<\/a> G<\/em> is defined as<\/p>\n

\"G<\/p>\n

where<\/p>\n