What is the primary function of a thermocouple?

The primary function of a thermocouple is to measure temperature differences. This device operates based on the fact that when two dissimilar metals are joined at two junctions, a voltage is generated that is proportional to the temperature difference between the junctions. As temperature changes occur, the voltage output varies accordingly, allowing for precise temperature measurements.

While thermocouples can generate a small voltage output due to temperature changes, their main purpose in applications is to serve as a temperature sensing device rather than a generator of electricity. Other choices such as measuring electric current or storing electrical energy do not align with the intended function of a thermocouple, which is specifically designed for temperature measurement.