@Epic2112@lemmy.world to No Stupid Questions@lemmy.world • edit-21 year agoIf incandescent lightbulbs have a vacuum inside, why do they get so hot on the outside?message-square50fedilinkarrow-up1116arrow-down13file-text
arrow-up1113arrow-down1message-squareIf incandescent lightbulbs have a vacuum inside, why do they get so hot on the outside?@Epic2112@lemmy.world to No Stupid Questions@lemmy.world • edit-21 year agomessage-square50fedilinkfile-text
minus-square@intensely_human@lemm.eecakelinkfedilink1•1 year agoHeat radiates as infrared light. Infrared doesn’t pass through glass well, so the glass absorbs the heat radiated from the filament. Heat passed through molecular collisions is conduction, and that is the part blocked by a vacuum. So the filament is emitting visible and infrared and the bulb is designed to let the visible pass through.
Heat radiates as infrared light. Infrared doesn’t pass through glass well, so the glass absorbs the heat radiated from the filament.
Heat passed through molecular collisions is conduction, and that is the part blocked by a vacuum.
So the filament is emitting visible and infrared and the bulb is designed to let the visible pass through.