What device uses the heating of two dissimilar metals to produce an electrical potential?

The device that uses the heating of two dissimilar metals to produce an electrical potential is a thermocouple. A thermocouple works based on the thermoelectric effect, specifically the Seebeck effect, where a voltage is generated when two different conductive materials are joined at two junctions and exposed to different temperatures. The temperature difference between the junctions causes charge carriers within the metals to move, which generates a measurable voltage. This technology is commonly used for measuring temperature in various applications, including industrial and scientific settings.

In contrast, a photocell operates on the principle of converting light energy into electrical energy, typically used in light-sensitive applications. A battery charger is designed to replenish stored electrical energy in batteries rather than generating electrical potential directly through temperature differences. A resistor is a component used to resist the flow of electric current, but it does not generate electrical potential nor does it involve dissimilar metals or temperature variations.