What is generated when the hot junction of a thermocouple is heated?

When the hot junction of a thermocouple is heated, a voltage is generated due to the thermoelectric effect, particularly the Seebeck effect. This phenomenon occurs because thermocouples are made of two different metals or semiconductors joined at one end (the hot junction) and left free at the other end (the cold junction). When the hot junction experiences a temperature difference compared to the cold junction, it creates a potential difference, which manifests as a voltage.

The amount of voltage produced depends on the types of materials used and the temperature difference between the two junctions. This principle allows thermocouples to be widely used for temperature measurement and sensing applications in various industries. Therefore, the key takeaway is that heating the hot junction directly leads to the generation of voltage, which can be measured to determine temperature.