Question

State any two differences between Peltier effect and Joule effect.

Answer 1

Hint:
Peltier effect and joule effect are both based on the heat. Both are different in the sense they are used for different aspects. It is due to their contrasting properties.

Complete step by step answer:
Let’s study about the Peltier effect.
A junction is composed of two materials. The heat will be generated in the upper material and absorbed in the lower material. This effect is called the Peltier effect. And this is the reverse of the phenomenon See back effect. The electric current is flowing through the two materials. Thus the heat is emitted or absorbed per unit area at the junction. The chemical potentials of the two materials will be balanced. And the heat absorbed or emitted will be proportional to the first power of the current. This effect can be applied in making refrigerators hence can be called as Peltier coolers.
And let’s look about the Joule effect. It describes that the heat is generated whenever voltage is applied across the resistive material. The heat emitted will be the square of the current.
The major differences of these two effects are:-
1) The Peltier effect is thermally reversible. But Joule effect is not reversible
2) In the Peltier effect the heat is generated at one junction and absorbed at another junction. While in Joule effect the heat is generated throughout the wire.

Note: While comparing both the effects, the Joule effect will have more heat generated hence it is square of current. The low cooling power of Peltier is beneficial in many applications.