27 December 2017

What is thermocouple

A thermocouple circuit made up from joining two wires of two dissimilar metals so due to the different effect net e.m.f is generated in the circuit which depends on the difference in temperature between the hot and the cold junctions.

This e.m.f can be measured by a microvoltmeter to a high degree of accuracy. The choice of selecting metal depends on the temperature range to be investigated, and copper constantan, chrome-alumni and platinum-rhodium are mostly used combinations. 

Advantages of a thermocouple are that it comes to thermal equilibrium with the system, whose temperature is to be measured, quite rapidly, because its mass is small.

Different effect to generate net e.m.f is :
  • Seebeck effect 
  • Peltier effect
  • Thomson effect