The amount of heat energy absorbed or evolved at one of the junctions of a thermocouple when one-ampere current flows for one π second (one coulomb) is called Peltier coefficient. It is denoted by π. Its unit is volt. If H is the quantity of heat absorbed or evolved at one junction then H = π It
The Peltier coefficient at a junction is the Peltier emf at that junction. The Peltier coefficient depends on the pair of metals in contact and the temperature of the junction.