1. What is a Thermo couple? 2. What is Thomson effect?

A thermocouple consists of two conductors of different materials (usually metal alloys) that produce a voltage in the vicinity of the point where the two conductors are in contact. The voltage produced is dependent on, but not necessarily proportional to, the difference of temperature of the junction to other parts of those conductors.

 

When a current flows through an unequally heated metal, there is an absorption or evolution of heat in the body of the metal. This is Thomson effect.