**2.2 Thermocouple**

Thermocouples represent a popular and highly effective temperature measurement technology that relies on the variation of thermoelectric potential difference generated at the contact point with temperature change. The selection of thermocouple materials is based on criteria, such as chemical stability and high thermal response electromotive force, which can impact measurement accuracy. Moreover, the accuracy of a thermocouple depends on its class of manufacturing tolerance. Common thermocouple

**Figure 1.** *The mercury thermometer.*
