Mathematical and Physical Bases for Incandescent Lamp Exponents

Mathematical equations connecting incandescent lamp operating characteristics have two uses: (1) as computational tools, and (2) as means of discovering physical principles involved in the operational behavior of lamps. The only equations which have been used to any great extent for the first of these purposes are those involving the so-called lamp exponents. The physical basis for the behavior of incandescent lamps is found in the variation of various properties of tungsten with temperature. A simple theoretical derivation of the lamp exponents has been developed. The simplified theory as presented gives results that are close enough to the observed behavior of lamps that corrections to the theory for end effects, blackbody effect of helical coils, etc., should be possible without the need of excessive elaborations.