Also the chemical involve in the W and iodine. Thx
Welcome to PF.
Your question is unclear.
Do you mean an incandescent lamp with a tungsten filament?
There are no chemical reactions to make the filament glow - the metal heats up until it glows. Reactions with air will reduce the lifetime of the bulb so we want to avoid them.
Don't know what you mean by "in the W and iodine".
I suppose he refers to halogen lamps. There some halogen like iodine is added to the gas surrounding the filament. It reacts with the tungsten at the cooler quartz surface (which still has some hundred degrees centigrade) to form tungsten iodide which vaporizes and diffuses back to the filament where it decomposes again into tungsten and elementary iodide. This helps to prolong the livetime of the lamp and use them at higher filament temperatures.
PS: Maybe more adequate to be discussed in the chemistry forum
sorry for unclear question, I want to know what happen in the incandescent lamp which add 0.1 mg of iodine. Thx for DrDu, I can picture something.
You may also look for: Van Arkel - de Boer method
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