Question

Which of the following is a characteristic temperature for the thermocouple?

• A. Temperature of cold junction
• B. Temperature of hot junction
• C. Temperature of inversion
• D. Neutral temperature

Answer 1

Answer: (D)

Neutral temperature

Answer 2

Thermocouple is based on See beck effect. If one junction is at $0^{\circ} C$ and the other att ${ }^{\circ} C$, then the thermo emf is given by $E=a t + b t^{2}$ where a and b are constants for the pair of metals. As the temperature of the hot junction rises, the thermo emf increases and becomes maximum at a particular temperature. This temperature is called neutral temperature and has different values for different pairs of metals. Temperature at which thermo emf becomes zero is called inversion temperature. Hence, neutral temperature is a characteristic temperature.