What physical principle allows a thermocouple to measure temperature?

A thermocouple measures temperature based on the thermoelectric effect, which is the principle underlying its operation. Specifically, a thermocouple consists of two different metals joined at one end, and when the junction experiences a temperature difference compared to the other ends of the wires, it generates a voltage. This phenomenon is due to the Seebeck effect, which is a specific case of the thermoelectric effect.

The voltage produced by a thermocouple is directly related to the temperature difference between the sensing junction and the reference junction. This relationship allows for precise temperature readings across a wide range of environments, making thermocouples widely used in various industrial applications.

The relationship between voltage and temperature difference is indeed crucial in using thermocouples effectively, but the fundamental phenomenon at play is the thermoelectric effect itself. Understanding this distinction is important for accurately interpreting how and why thermocouples function as they do.