Heat and Thermodynamics

11.13 Jaeger and Diesselhorst Method

Kohlrausch introduced a method of determining the ratio of thermal to electrical conductivity. He pointed out that a simple way of determining the thermal conductivity of a metal is to measure the temperature distribution in the metal when it is heated by an electric current. The theory of this method depends upon the fact that when a steady state has been reached, the heat gained by any element by conduction plus the heat generated by the electric current in the element is zero. This was experimentally worked out by Jaeger and Diesselhorst. The theory of this method is as follows:

Let us take the case of a solid cylinder of metal of which the thermal conductivity is to be determined. We assume that the current ...