What is the Seebeck effect?
When two wires of different metals or metal alloys (thermo wires) are joined together in one end (hot junction), a thermocouple is formed. If there is a temperature difference between the hot junction and the open ends, a thermal electromotive force (a thermal voltage) is created in the thermocouple. This is also called the Seebeck effect. More details on page How does a thermocouple (TC sensor) work?