Thermocouples are created when two different metals are joined together at a junction. Connecting the other ends of these dissimilar metals at another junction establishes an electrical circuit.

  • Temperature Sensitivity: A current will flow in the circuit if the temperatures at the two junctions differ.
  • Electromotive Force (EMF) Differences: The current generated is due to the variance in electromotive force (EMF) created at the two junctions resulting from the temperature difference between them.
  • Voltage Measurement: The voltage difference between the two junctions is measured, and this difference is directly proportional to the temperature disparity between them.
  • Temperature Differences: It’s important to note that thermocouples are specifically designed to measure temperature differences.

Effects Associated with Thermocouples

  • The Seebeck Effect:
    This effect indicates that the voltage generated in a thermocouple is directly proportional to the temperature difference between its two junctions.
  • The Peltier Effect:
    It describes that when a current passes through a thermocouple, one junction gets heated (releasing energy) while the other junction is cooled (absorbing energy).
  • The Thompson Effect:
    When a current flows through a conductor experiencing a temperature difference, heat can be either generated or absorbed, based on the current’s direction and the temperature variation.