when the junctions of two dissimilar metals are maintained at different temperatures an electromotive force is set up in the circuit of which these junctions are part. a pair of junctions of this kind and the effect are known respectively as
thermocouple and seebeck effect
The phenomenon you are referring to is called the "Seebeck effect." When two dissimilar metals are connected to form a circuit, and the junctions of these metals are at different temperatures, an electromotive force (EMF) is generated in the circuit. This EMF produces an electric current that flows through the circuit.
The pair of junctions that exhibit this effect are known as "thermocouples." A thermocouple consists of two different types of conductors, usually made of different metals, connected at two junctions. One of these junctions is at a known reference temperature, while the other junction is exposed to the temperature being measured. As temperature difference occurs between the two junctions, an EMF is generated, which can be measured using a voltmeter.
The Seebeck effect and thermocouples have various applications, such as temperature sensing and measurement in industries, scientific experiments, and even household appliances.