Explanation

When direct current passes through a uniform metal or semiconductor with a temperature difference, in addition to Joule heat, it also releases or absorbs heat; On the contrary, when the temperature at both ends of a metal rod is different, a thermoelectric phenomenon of potential difference will form at both ends. Thomson heat Q=r/AT, where r is the Thomson coefficient, V/K; J is the current, A. For metal or N-type semiconductors? When the current flows from high temperature to low temperature, the heat released by materials. r is positive; On the contrary, it is negative. For P-type semiconductors, the situation is the opposite. R can be derived from the Seebeck coefficient of materials, which is called the the second Kelvins relationship. Compared with the Peltier effect, the Thomson effect is generally small and often ignored. The Thomson effect, Seebeck effect, and Peltier effect are different but related thermoelectric effect of materials, and they are reversible.

Classification