What describes a thermocouple's behavior in relation to temperature?

A thermocouple operates based on the thermoelectric effect, which is the principle behind its function of measuring temperature. When the junctions of two different metals are subjected to a temperature difference, they generate a voltage that is proportional to that difference. This means that as temperature rises, the generated voltage changes in a way that correlates with the change in temperature.

Specifically, in most cases, as the temperature increases, the resistance of the thermocouple materials tends to decrease. This change in resistance is part of what allows the thermocouple to be a reliable temperature measurement device. Because of this behavior, it is important to understand that thermocouples do not maintain a constant resistance; rather, their resistance usually decreases with an increase in temperature, making them sensitive to variations in thermal conditions.

The calibration aspect is also vital in thermocouples. They require specified calibration to ensure accurate temperature readings, but this is regarded as a separate requirement from the direct behavior of resistance with temperature changes. Understanding the relationship between resistance and temperature is crucial in utilizing thermocouples effectively in various applications.