Light bulb and a microwave
Why does a light bulb light up a purple color when you
put it in the microwave?
Sounds like you have been doing some hazardous experiments
at home there... In fact, I have never heard of this before -
and I cannot think of an explanation either. Sorry. Light bulbs
have tungsten filaments and some gas (Argon I think) inside,
and microwaves generate relatively high-frequency radiation.
I assume the tungsten is absorbing most of the radiation and
heating up, but not quite as hot as it normally gets when
the light bulb is plugged in. But that is just a guess.
Normal light bulbs have only a partial vacuum in them; that
is, they have a small gass pressure inside, or a small amount of
gas (usually argon) in them. The microwave radiation is creating
a plasma in the gas, which emits light.
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Update: June 2012