Lecture
In 1823 T. Seebeck established that in a circuit consisting of two dissimilar conductors 1 and 2, an electromotive force VT arises if the contacts of these conductors A and B are maintained at different temperatures Тг and Тх (fig.
2.4). This EMF is called the thermoelectromotive force.
Fig. 2.4. Thermoelectromotive force in a circuit of two dissimilar conductors
As experiment shows, over a relatively narrow temperature range it is proportional to the temperature difference between contacts А and В:
VT = α(Тг −Тх).
The proportionality coefficient
α = dVT /dT
is called the differential or specific thermoEMF. It depends on the nature of the contacting conductors and on temperature.
There are two main sources giving rise to the thermoEMF: the change of the contact potential difference with temperature (the contact component Vк) and the formation of a directed flux of carriers in a conductor in the presence of a temperature gradient (the volume component Vоб).
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