It is a device used to detect and measure the intensity of heat radiations.

    For a given small difference in temperature of two junctions of a thermocouple, Bi - Sb thermocouple produces a comparatively large e.m.f. and it can be used to detect the heat radiation when a number of such thermocouple are connected in series, the arrangement becomes very much sensitive to detect heat radiation as the thermo e.m.f.s of the thermocouple get added.

    Applications of thermoelectric effect