Electrical resistivity and conductivity conductivity in a solution. A rough summary is as follows: This table shows the resistivity (ρ), conductivity and temperature coefficient of various materials at 20 °C (68 °F, 293 K) The effective temperature coefficient varies with temperature and purity level of the material. The 20 °C value is only an approximation when used at other temperatures. For example, the coefficient becomes lower at higher temperatures for copper, and the value 0.00427 is commonly specified at . The extremely low resistivity (high conductivity) of silver is characteristic of metals. George Gamow tidily summed up the nature of the metals' dealings with
Thermal conductivity given thickness of a material, that particular sample's "thermal resistance" and the reciprocal property, "thermal conductance", can be calculated. Unfortunately, there are differing definitions for these terms. Thermal conductivity, "k", often depends on temperature. Therefore, the definitions listed below make sense when the thermal conductivity is temperature independent. Otherwise a representative mean value has to be considered; for more, see the Equations section below. For general scientific use, "thermal conductance" is the quantity of heat that passes in unit time through a plate of "particular area and thickness" when its opposite faces differ in temperature by one kelvin. For a