What is Peltier effect ?

Explanation

(i) When an electric current is passed through a circit o a thermocopule, heat is evolved at one juction and absorbed at the other junction. This is known as Peltier effect.
(ii) In the Cu-Fe thermocopule the junctions A and B are maintained at the same temperature.
(iii) Let a current from a battery flow through the thermocouple. At the junction A, where the current flows from Cu to Fe, heat is absorbed and the juction A becomes cold.
(iv) At the junction B,where the current flows from Fe to Cu heat is liberated and it becomes hot.

(v) When the direction of current is reversed, junction A gets heated and junction B gets cooled as shown in the figure 2.36 (b). Hence Peltier effect is reversible.