What device converts heat to electricity?

A thermocouple is the correct answer because it is a device specifically designed to convert thermal energy (heat) into electrical energy through the Seebeck effect. This effect occurs when two different metals are joined together at two junctions, creating a voltage difference proportionate to the temperature difference between the junctions. As a result, thermocouples are widely used for temperature measurement in various industrial applications because the generated voltage can be accurately correlated to temperature readings.

In contrast, a resistance temperature detector is used to measure temperature by correlating the resistance of the sensing element to temperature changes, but it does not convert heat to electricity in the same manner as a thermocouple. A bimetallic temperature gauge relies on the mechanical movement of two different metals bonded together to measure temperature, while a thermowell is a protective tube that houses a temperature sensor but does not perform the function of converting heat to electricity.