Wiedeman- Franz law

Adequate prediction of the thermal conductivity for pure metals can be made by means of the Wiedeman-Franz law which states that the ratio of the thermal conductivity to the product of the electrical conductivity and the absolute temperature is a constant. This ratio for... 

Bridges give a mean resistance value around 7 = 0. Strictly, they should be used only for linear components. In both cases (d.c. or a.c.), the resistance measurements are made in four-wire configuration, since the resistor to be measured is at low temperature whereas the measuring instrument is at room temperature the electric connection is usually made by low thermal conductivity wires which are also poor electrical conductors (remind the Wiedeman-Franz law). 

Adequate prediction of the thermal conductivity for pure metals can be made by means of the Wiedeman-Franz law which states that the ratio of the thermal conductivity to the product of the electrical conductivity and the absolute temperature is a constant. This ratio for high-conductivity metals extrapolates essentially to the Sommerfeld value of 2.449 x 10" W f2/K at 0 K, but falls considerably below it at higher temperatures. High-purity aluminum and copper exhibit peaks in thermal conductivity between 20 to 50 K, but these peaks are rapidly suppressed with increased impurity levels and cold work of the metal. Some metals including Monel, Inconel, stainless steel, and structural and aluminum alloys show a steady decrease in thermal conductivity with a decrease in temperature. 

Weight - That force which, when applied to a body, would give it an acceleration equal to the local acceleration of gravity. [1] Wiedeman-Franz law - The law stating that the thermal conductivity k and electrical conductivity a of a pure metal are related hyk = LaT, where T is the temperature and L (called the Forenz ratio) has the approximate value 2.45 x 10" W/IG. Wien displacement law - The relation, which can be derived from the Planck formula for black body radiation, that... 

In metals the conductivity decreases with temperature according to the Wiedeman-Franz law. 

---