Question
If the cold junction of a thermocouple is kept at $${0^ \circ }C$$ and the hot junction is kept at $${T^ \circ }C,$$ then the relation between neutral temperature $$\left( {{T_n}} \right)$$ and temperature of inversion $$\left( {{T_i}} \right)$$ is
A.
$${T_n} = \frac{{{T_i}}}{2}$$
B.
$${T_n} = 2{T_i}$$
C.
$${T_n} = {T_i} - T$$
D.
$${T_n} = {T_i} + T$$
Answer :
$${T_n} = \frac{{{T_i}}}{2}$$
Solution :
It is found that temperature of inversion $$\left( {{T_i}} \right)$$ is as much above the neutral temperature $$\left( {{T_n}} \right)$$ as neutral temperature is above the temperature of the cold junction $${T_0},$$ i.e.
$$\eqalign{
& {T_i} - {T_n} = {T_n} - {T_0} \cr
& {\text{or}}\,\,{T_i} = 2{T_n} - {T_0} \cr} $$
But, here the cold junction is kept at $${0^ \circ }C.$$
Thus, $${T_i} = 2{T_n}\,\,{\text{or}}\,\,{T_n} = \frac{{{T_i}}}{2}$$