How does a thermocouple use the Seebeck effect to measure temperature?

A thermocouple measures temperature by utilizing the Seebeck effect, which occurs when two dissimilar conductors (typically metals or alloys) are joined at two junctions maintained at different temperatures.12

In this setup, one junction is placed in the environment where the temperature is to be measured, while the other is kept at a known, constant reference temperature. Because the two metals have different temperature-dependent Fermi levels, the temperature gradient between the junctions generates a net electromotive force (emf) within the circuit.32

This generated emf is approximately proportional to the temperature difference between the two junctions. By measuring this voltage with a connected instrument, the temperature can be determined either by referencing standard tables or by calibrating the instrument to provide a direct reading. The choice of materials for the thermocouple is dictated by the required sensitivity and the specific chemical properties of the medium being measured.23