Notes

Variation of Thermo-Emf with Temperature…

Variation of Thermo-Emf with Temperature – In a thermocouple as the temperature of the hot junction at constant temperature (say 0° C), the thermo-emf increase till it becomes maximum at a certain temperature.
(i) Thermoelectric emf is given by the equation E = αt + 1/2βt²
i.e. α + βt_n = 0 ⇒ -α/β
(ii) Neutral temperature is independent of the temperature of cold junction,
(iii) Relation between t_n, t_i and t_c is t_n = t_i + t_c/2,
(iv) At neutral temperature, thermoelectric power is zero.