If incandescent lightbulbs have a vacuum inside, why do they get so hot on the outside?
Shouldn't the vacuum insulate the glass from the heat of the burning filament?
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Shouldn't the vacuum insulate the glass from the heat of the burning filament?
Vacuum means no convection heat. It however does not mean no radiation heat. The filament radiates heat through vacuum the same way the sun does.
Additionally, theres not vacuum in buldbs, but inert gas, like argon.
There no longer is a vacuum in bulbs, but there was for a very long time.
"Halogen" bulbs are just incandescent bulbs filled with inert gas and a small amount of bromine or iodine. Very interesting chemistry https://en.wikipedia.org/wiki/Halogen_lamp