Question

The constants a and b for the pair silver-lead are 2.50 μV°C−1 and 0.012μV°C−2, respectively. For a silver-lead thermocouple with colder junction at 0°C,
(a) there will be no neutral temperature
(b) there will be no inversion temperature
(c) there will not be any thermo-emf even if the junctions are kept at different temperatures
(d) there will be no current in the thermocouple even if the junctions are kept at different temperatures

Answer 1

Explanation:

• The hot junction’s temperature in a thermocouple at which the thermo-emf becomes the maximum is known as the neutral temperature. The constants’ signs a and b are the same. So, from the relation, θn = -ab.

• More than the cold junction’s temperature, the neutral temperature will be less in the thermocouple.

• Therefore, there will be no inversion temperature or the neutral temperature. This is because that cold junction’s temperature is more than the hot junction.