A thermocouple is a device used to measure temperature by utilizing a pair of dissimilar metal wires welded at one end. The variation in temperature between the two ends of the wires generates a voltage that is proportional to the temperature difference. This voltage can be measured by a voltmeter, which then converts it into a temperature reading.
Thermocouples are widely used in industrial and scientific applications for their accuracy, reliability, and relatively low cost. They are also commonly used in everyday devices such as ovens, refrigerators, and thermometers.