ABSTRACT
Thermodynamics is an efficient means of finding most general regularities in the theory of
thermoelectricity.
In 1854, W. Thomson
using equilibrium thermodynamics established the interrelation between three
thermoelectric effects that arise in a thermocouple thermoelectric circuit with the legs of individual
isotropic media (Figure 2.1) in the form of relationships
dP=dT 2 a2 t ¼ 0 ð2:1Þ
dP=dT 2P=T 2 t ¼ 0 ð2:2Þ
where a is the Seebeck coefficient, P is the Peltier coefficient, and t is the Thomson coefficient. Equation
2.1 and Equation 2.2 imply two relationships of frequent use in thermoelectricity:
P ¼ aT is the first Thomson relationship ð2:3Þ
t ¼ Tð›a=›TÞ is the second Thomson relationship ð2:4Þ
It is common knowledge today that a rigorous thermodynamic theory of thermoelectricity can be
constructed only on the basis of a nonclassical, more general theory of macroscopic description of
nonequilibrium processes called nonequilibrium thermodynamics or thermodynamics of irreversible
processes.
