Question

Consider the following two statements A and B and identify the correct answer :
A: Constantan - Copper thermocouple is generally used to measure temperatures upto ${1600}^{o}C$
B: In an iron - copper thermocouple, current flows from iron to copper through cold junction.

• A. Both A and B are true
• B. Both A and B are false
• C. A is true but B is false
• D. A is false but B is true

Answer 1

Answer: (D)

A is false but B is true

For low temperature measurement: Constantan-iron thermo-couple and constantan-copper couple are used to measure low temperature upto 18K. And for High temperature measurement: they are used to measure high temperature up to 300 degree Celsius.

So A is false

Since the thermoelectric current flows from a metal earlier in the series to a metal later in the series thermo electric current flows from Fe to Cu at the cold junction of the thermo-couple. hence B is correct.