The temperature of inversion of a thermocouple is 620°C and the neutral temperature is 300^oC, what is the temperature of cold junction?

• 20^o C

• 320^o C

• -20^o C

• 40^o C

C.

-20^o C

The temperature of inversion is higher than the neutral temperature by the same amount as the neutral temperature is higher than the temperature of cold junction.

As per the above statement

t_n - t₀ = t_i - t_n

⇒ t₀ = 2t_n - t_i

Given, t_i = 620^o C, t_n =300^o C

Hence,  

t_o = temperature of cold junction

   = 2 × 300 - 620

t_o = -20^o C

Neutral temperature does not change for a metal whether the temperature of cold junction and inversion temperature change by any value.