Question

Explain neutral and inversion temperatures with the help of a graph between the thermo emf and the temperature of the hot junction in a thermocouple.

Answer 1

Here, $T_c$ is the temperature of the cold junction which is maintained at $0^{o}C$.
$T$ is the temperature of the hot junction.
$T_n$ is the neutral temperature and $T_i$ is the inversion temperature.
The temperature of the hot junction at which thermo-emf in the thermocouple becomes maximum is called neutral temperature $T_n$ for that thermocouple. For a given thermocouple, $T_n$ has a fixed value.
On further increasing the temperature of the hot junction,after $T_n$ has reached, the thermo-emf decreases and becomes equal to $0^{o}C$ at a particular temperature called temperature of inversion $T_i$.