Quote:
Originally Posted by frazod
Actually, that's not true. My new microwave has a metal rack in the middle. I have no idea what keeps it from exploding, but it's definitely metal.
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http://lohdown.caltech.edu/script_archiv...
"Metal in Microwaves
Hey--how come you can't put aluminum foil into a microwave, but microwaves now come with metal racks? Are the pranksters at Panasonic TRYING to burn my kitchen down?
Physics offers an answer.
Microwave ovens produce electromagnetic waves that jiggle electrons--the negatively-charged bits inside atoms--kind of like ocean waves bob buoys up and down. Jiggling electrons represent kinetic energy -- motion at the atomic level-- and produce heat. The same jostling happens with water molecules--and THAT motion heats up your food.
The electrons in metal are mobile--they can move freely among atoms--and that's where microwave problems start. A thin metal like aluminum foil doesn't have room for all the wiggling, roving electrons. Instead, they bang into aluminum atoms, and then other aluminum atoms, and the FOIL heats up, catches fire, next thing you know, handsome firemen feel. . . you're wasting their time.
Sharp edges and points -- like on a fork--can also be prickly. The problem here? Static electricity. Electrons congregate in the edges and points, building up negative charge. Eventually, they start leaping off, causing sparks .. think mini-lightning.
But when the metal is thick, smooth, with rounded edges--that metal rack--the moving electrons can bounce around freely while rarely hitting another metal atom. Rack doesn't get hot.
Thanks for messing with my head, microwave people. But drying a poodle in the microwave, that's okay, isn't it? No. Just kidding! Don't! "
also read the faq from whirlpool
http://food.rediff.com/whirlpool/html/ma...
"Q: Why metal rack can be used in the combination mode?
A: In the combination mode, the microwave is used only for a short duration in the microwave mode when metal rack cannot and shouldn't be used. The rack has no sharp edges and the gap between the rods of the rack is large enough to prevent sparking and to allow the microwave to pass through. Please note the grill rack is only to elevate the food to come closer to quartz heater element for faster browning."