Dang has two species different of conductor or semiconductor a, and b composition a loop, its ends mutual connection Shi, as long as two knot points at of temperature different, end temperature for t, called work end or hot end, another end temperature for T0, called free end (also said reference end) or cold end, loop in the will produced a electric potential, the electric potential of direction and size and conductor of material and the two contact of temperature about. This phenomenon is known as "thermoelectric", two conductor circuit known as "thermocouples", these two conductors are called "heat", the resulting electromotive force is called "thermal EMF.
Thermal EMF electromotive force composed by two parts, part two-conductor contact electromotive force, another part of the thermoelectric effect of a single conductor.
Thermoelectric in a thermocouple circuit size, with only two contacts and conductors of the thermocouple material temperature, and has nothing to do with the shape and size of the thermocouple. When the thermocouple fixed electrode materials for two, thermal EMF is the two-junction temperature t and T0. Poor function. That this relationship has been widely applied in the actual temperature. Cold end-t0-constant thermocouple thermoelectric hot (measuring end) regardless of changes in temperature, namely certain thermoelectric voltage corresponding to a certain temperature. We'll just use thermoelectric measurement methods can achieve the purpose of measurement.