device consisting of two wires of different metals joined at their ends to form a loop; when a temperature difference between the two junctions unbalances the contact potentials, a current will flow round the loop. If the temperature of one junction is kept constant, that of the other is indicated by measuring the current, or more usually the potential difference set up when the circuit is open. Conversely, a current driven round the loop will cause a temperature difference between the junctions.
