Thermoelectricity
. Thermoelectricity, in physics, electricity generated by the application of heat to the junction of two dissimilar materials. If two wires of different materials are joined at their ends and one end is maintained at a higher temperature than the other, a voltage difference will arise, and an electric current will exist between the hot and the cold junctions. This phenomenon was first observed in 1821 by the German physicist Thomas Seebeck and is known as the Seebeck effect. For a given combination of materials, the voltage difference varies in direct proportion to the temperature difference. This phenomenon can be utilized for the accurate measurement of temperature by means of a thermocouple in which one wire junction is maintained at a known reference temperature (for example, in an ice bath) and the other at the location where the temperature is to be measured. At moderate temperatures (up to about 260° C/500° F), wire combinations of iron and copper, iron and constantan (a copper-