The Thermocouple Revisited: The Benedicks and Seebeck Effects

Abstract

Abstract Through altering the ambient environment of the iron conductor with respect to the copper conductor of an iron-copper thermocouple, the output emf of the thermocouple was reduced by a factor of almost two. This reduction was apparently a result of a Benedicks emf. Such a Benedicks emf was produced here in a continuous iron conductor. The Benedicks emf produced was about half the expected Seebeck emf from the copper-iron couple. The source of the Benedicks emf can be explained as a Seebeck charge separation produced by the effect of ambient radiation in one conductor of the thermocouple, while the effect of ambient radiation was deliberately removed in the other part of the conductor. The effect of ambient radiation was removed by matching the surface temperature gradient of the second part of the conductor point for point with an external (or ambient) temperature gradient. The conclusions of this research contradict the assumption made by William Thomson [1] that the ambient surroundings have no effect on thermocouple behavior. This assumption, which was made almost two hundred years ago, has never been experimentally refuted. The idea of using such a temperature match arose from a lesson learned from observations of directly measured Thomson coefficients by Jacovelli et al. [2]