Dimming behaviour of incandescent lamps. Relative luminous flux F and colour temperature in dependence on the relative voltage U/Un. Voltage reduction causes an over-proportional drop in luminous flux.
Halogens in the gas filling reduce the material loses of the filament caused by evaporation and increase the performance of the lamp. The evaporated tungsten combines with the halogen to form a metal halide, and is channelled back to the filament. The lamp's compact shape not only enables the temperature to increase but also allows an increase in the gas pressure, which reduces the tungsten's rate of evaporation. As the temperature increases the light spectrum shifts towards the short wavelength range - the red heat of the filament becomes the warm white light of the incandescent lamp. A lot of thermal radiation is generated in comparison to the visible component; conversely there is very little UV radiation. The tungsten halogen reflector lamp emits a continuous spectrum and thus produces an excellent
colour rendition.
