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 remaining 3"p"("q" − 1) are accommodated through the optical branches. This implies that structures with larger "p" and "q" contain a greater number of optical modes and a reduced "λ". From these ideas, it can be concluded that increasing crystal complexity, which is described by a complexity factor CF (defined as the number of atoms/primitive unit cell), decreases λ. This was done by assuming that the relaxation time "τ" decreases with increasing number of atoms in the unit cell and then scaling the parameters of the expression for thermal conductivity in high temperatures accordingly. Describing of anharmonic effects is complicated