Automobile headlamps generally have incandescent, halogen, xenon gas type, etc.
With the continuous development of auto technology, the old incandescent light vacuum has been has been eliminated.
Now car headlamps is given priority to with halogen lamp and xenon lamp.
Halogen lamp, it is inside the bulb into a small amount of iodine of inert gas, from the tungsten filament evaporation and iodine atoms reaction, generate iodide tungsten compound, when tungsten iodine compound contact white-hot filament (
Temperature over 1450 ℃)
Reduction of tungsten and iodine and decomposition, tungsten and returned back to the filament, iodine back into the air.
Almost won't burn out, so circulates, filament bulbs will not black, so it is better than traditional incandescent light live longer, more brightness.
Now cars generally used are the headlamps.