Metal in a Microwave
Name: Amal A.
Why can not we put a metal in a microwave oven?
A microwave oven sends waves at whatever we put in. The waves are set such
that water molecules absorb them very well, changing the radiation energy
into heat energy. Metal will absorb microwaves, but it will not change the
radiation energy into heat energy. The metal re-emits the radiation energy:
very much like visible light reflecting from the metal coating of a mirror.
More and more radiation energy is added to the oven, but none gets absorbed.
Eventually the amount of radiation energy is great enough to cause sparks to
fly, possibly causing a fire.
Dr. Ken Mellendorf
This answer suggests energy builds up in the microwave oven if metal is
present. This is 100% wrong, and is about as silly as saying leaving the
lights on in a room with a mirror will make the room get brighter and
brigher until we are all blinded.
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Update: June 2012