Physics · Ch 2 — Current Electricity
Peltier Effect
Peltier Effect
Peltier, in 1834, discovered the reverse-direction phenomenon: when an electric current is passed THROUGH a thermocouple circuit (rather than a temperature difference producing a current, as in the Seebeck effect), heat is found to be evolved at one of the two junctions and absorbed at the other. This is called the Peltier effect.
In a copper-iron thermocouple with both junctions A and B initially at the same temperature (Figure 2.36), if a current from a battery is driven through the loop such that current flows from copper to iron at junction A, heat is absorbed there and junction A becomes cold; simultaneously, at junction B, where current flows from iron to copper, heat is liberated and junction B becomes hot. If the direction of the current is reversed, the roles of the two junctions swap exactly -- jun …
What this figure shows. Panel (a) shows a copper-iron thermocouple with junctions A and B initially at the same temperature; a battery drives a current through the loop in a particular direction, and where the current flows from Cu to Fe (at junction A) heat is shown being absorbed, making A the 'Cold Junction', while where current flows from Fe to Cu (at junction B) heat is shown being liberated, making B the 'Hot Junction'. Panel (b) shows the same thermocouple with the battery's polarity reversed, so the current direction flips and, correspondingly, junction A is now shown as the 'Hot Junction' and junction B as the 'Cold Junction' …