Which device is constructed using two dissimilar metals, such as chromel and constantan?

A thermocouple is a device that is specifically designed to measure temperature by utilizing the principle of thermoelectricity. It consists of two dissimilar metals, such as chromel (an alloy of nickel and chromium) and constantan (an alloy of copper and nickel). When these metals are joined together and subjected to a temperature difference, they produce a voltage that can be interpreted to determine the temperature at the junction.

The use of dissimilar metals is crucial because the differing properties of the metals lead to the creation of a voltage that is proportional to the temperature differential. This voltage can be measured and converted into a temperature reading, making thermocouples an effective tool for temperature sensing in various applications, including powerplant fire detection systems.

In contrast, a thermal switch operates differently by opening or closing circuits based on a specified temperature threshold without generating a voltage for measurement. Continuous loop detectors are systems designed to detect fires and typically employ different technologies rather than relying on the combination of two metals. Inert agents refer to substances used in fire suppression and do not relate to temperature measurement or the properties of dissimilar metals.