Where does this come from, and can I check it?

A halogen gas carries evaporated metal back instead of letting it coat the glass. The figure is taken from National Institute of Standards and Technology, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a everyday life fact?

Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

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The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Halogen bulbs recycle tungsten back onto the filament

A halogen gas carries evaporated metal back instead of letting it coat the glass In an ordinary incandescent lamp, tungsten evaporates from the filament and darkens the envelope. Adding a trace of halogen, usually iodine or bromine, creates a cycle in which tungsten vapour combines near the cooler glass wall and is returned to the hot filament. The filament can therefore run hotter, giving a whiter light and a longer life from a smaller bulb. It sits in Mondo's everyday life collection, one of 200 facts that each trace back to the reference below.

Where this comes from

National Institute of Standards and Technology

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Tags: lighting, chemistry, bulbs

Halogen bulbs recycle tungsten back onto the filament: the short answers

Where does this come from, and can I check it?: A halogen gas carries evaporated metal back instead of letting it coat the glass. The figure is taken from National Institute of Standards and Technology, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a everyday life fact?: Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.