What is the thermometric property of a thermocouple? (7) - Leaving Cert Physics - Question (c) - 2005

The thermometric property of a thermocouple refers to its capability to convert temperature differences into an electrical voltage. This property is based on the thermoelectric effect, specifically the Seebeck effect, where a temperature gradient between two junctions of different metals generates an electromotive force (emf).

In practical terms, this means that when two dissimilar conductive materials are joined at two points and those points are maintained at different temperatures, a voltage is produced that is proportional to the temperature difference between the junctions. The emf can be expressed mathematically:

$E ext{ (emf)} = S imes (T_1 - T_2)$

where:

• $E$ is the generated voltage (emf),
• $S$ is the Seebeck coefficient (which depends on the materials used),
• $T_1$ and $T_2$ are the temperatures at the hot and cold junctions, respectively.

This voltage can then be measured and used to accurately determine temperatures, making thermocouples a popular choice in temperature measurement applications.