Question

Thermoelectric current at the temperature of inversion
A. flows from copper to iron through a hot junction.
B. flows from iron to copper through a hot junction.
C. is maximum.
D. does not depend on the temperature of the cold junction.

Answer 1

Thermoelectric effect is the conversion of temperature difference to the electrical potential difference or vice versa through a device known as thermocouple. A thermocouple is an electrical device consisting of two different electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage due the thermoelectric effect and this voltage can be interpreted to measure temperature.

Complete answer:
The emf produced due to the result of the temperature difference is known as thermo emf. The temperature at which the thermo emf changes its sign is called temperature inversion. And the thermo emf is zero at a hotter junction.
So at temperature inversion the thermo electric current will be maximum and will decrease at temperature inversion.

So the correct option is C.

Additional Information:
Thermoelectric effect is the production of potential difference due to temperature difference with the help of a device called thermocouple.
Thermoelectric effect consists of three separate effects (i)Seebeck effect(ii)Peltier-effect(iii)Thompson effect.
(i) Seebeck effect: It is the production of electric potential difference whenever there is a temperature gradient.
(ii) Peltier effect: Whenever a current is passed through a thermocouple at one end the heat is absorbed and at the other end heat is produced. This is called the peltier effect.
(iii) Thompson effect: The occurrence of seebeck as well as peltier effect in the same material is called Thompson effect.

Note:
Thermoelectric effect happens because with application of temperature gradient(change in temperature with respect to position) to a material results in diffusing the change carrier (electrons or hole) from hotter side to colder side. Thermoelectric effect can be used for generation of electricity. It can also be used to measure the temperature of an object or to measure the temperature difference of the objects. This is due to the direction of cooling or heating is affected by the applied voltage. So Thermoelectric materials are used as temperature sensors.
Note that the thermoelectric effect and heating effect of electric current is not generally equal. The heating effect arises due to the collision of the charge carriers whereas in thermocouple the current is produced due to the temperature gradient. Some special materials can be used as thermocouple.