Joined in 2023 
82 
63 About this deal
This allows the filament to operate at a higher temperature than a standard incandescent lamp of similar power and operating life; this also produces light with higher luminous efficacy and color temperature. The bulb must be made of fused silica (quartz) or a high-melting-point glass (such as aluminosilicate glass).
Tungsten halogen lamps behave in a similar manner to other incandescent lamps when run on a different voltage. of multifaceted reflector "MR" lamps of 20–50 watts were originally conceived for the projection of 8 mm film, but are now widely used for display lighting and in the home. A 300 watt tubular halogen bulb operated at full power quickly reaches a temperature of about 540°C (1,004°F), while a 500 watt regular incandescent bulb operates at only 180°C (356°F) and a 75 watt regular incandescent at only 130°C (266°F). The first lamps used only tungsten for filament supports, but some designs use molybdenum – an example being the molybdenum shield in the H4 twin filament headlight for the European Asymmetric Passing Beam.Regeneration of the filament is also possible with fluorine, but its chemical reactivity is so great that other parts of the lamp are attacked. At some point, however, it will reach higher temperature regions within the bulb where it then dissociates, releasing tungsten back onto the filament and freeing the halogen to repeat the process.
In ordinary incandescent lamps, evaporated tungsten mostly deposits onto the inner surface of the bulb, causing the bulb to blacken and the filament to grow increasingly weak until it eventually breaks. The use of iodine was proposed in a 1933 patent, [4] which also described the cyclic redeposition of tungsten back onto the filament.In June 2021, the UK government also announced plans to end the sale of halogen light bulbs from September, as part of the UK's wider efforts to tackle climate change. Halogen lamps made for 12 to 24 volt operation have good light outputs, and the very compact filaments are particularly beneficial for optical control (see picture).
However the light output is reported as proportional to V 3 {\displaystyle V The halogen cycle keeps the bulb clean and causes the light output to remain almost constant throughout the bulb's life. The combination of the halogen gas and the tungsten filament produces a halogen-cycle chemical reaction, which redeposits evaporated tungsten on the filament, increasing its life and maintaining the clarity of the envelope. Since quartz is very strong, the gas pressure can be higher, [14] which reduces the rate of evaporation of the filament, permitting it to run a higher temperature (and so luminous efficacy) for the same average life.More recently, wider beam versions have become available designed for direct use on supply voltages of 120 or 230 V. The small size of halogen lamps permits their use in compact optical systems for projectors and illumination. Incandescent lamp variety A halogen lamp operating in its fitting with the protecting glass removed A halogen lamp behind a round UV filter. The presence of the halogen, however, sets up a reversible chemical reaction cycle with this evaporated tungsten. At moderate temperatures the halogen reacts with the evaporating tungsten, the halide formed being moved around in the inert gas filling.
Quartz iodine lamps, using elemental iodine, were the first commercial halogen lamps launched by GE in 1959.The tungsten released in hotter regions does not generally redeposit where it came from, so the hotter parts of the filament eventually thin out and fail. For a fixed power and life, the luminous efficacy of all incandescent lamps is greatest at a particular design voltage. A carbon filament lamp using chlorine to prevent darkening of the envelope was patented [2] in 1882, and chlorine-filled "NoVak" lamps were marketed in 1892. Standard and halogen incandescent bulbs are much less efficient than LED and compact fluorescent lamps, and therefore have been or are being phased out in many places.
Great Deal 
New Comment