Seebeck effect
The Seebeck effect, named for Thomas Johann Seebeck (1770-1831), refers to the generation of a voltage potential, or emf, in an open thermocouple circuit due to a difference in temperature between junction in the circuit. The Seebeck effect refers to the case when there is no current flow in the circuit, as for an open circuit. There is a fixed, reproducible relationship between the emf and the junction temperature T1 and T2 (Fig. 8.13). This relationship is expressed by the Seebeck coefficient, αab, defined as where A and B refer to the two materials that comprise the thermocouple. Since the Seebeck coefficient specifies the rate of change of voltage with temperature for the materials A and B, it is equal to the static sensitivity of the open-circuit thermocouple.