Moving into my apartment, I was perplexed when I checked out my appliances. The stainless steel fridge and dishwasher were great upgrades, but the microwave made me pause. I spotted a rack inside, just like in a conventional oven. Ever since trying to soften a foil-wrapped pat of butter in the microwave as a kid, I've always known you weren't supposed to put metal in the microwave...

But apparently there's a reason you can leave that obviously metallic rack in the microwave. We checked out a script from a radio show out of the California Institute of Technology hosted by alumna Sandra Tsing Loh, "The Loh Down on Science," that gives us a clue:

Microwave ovens produce electromagnetic waves that jiggle electrons ... that motion [is what] 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 [and] catches fire. Sharp edges and points—like on a fork—can also be prickly. Electrons congregate in the edges and points, building up negative charge. Eventually, they start leaping off, causing sparks.

But when the metal is thick [and] smooth with rounded edges [like] that metal rack, the moving electrons can bounce around freely while rarely hitting another metal atom. [The] rack doesn't get hot!

Who knew? There was a simple physics answer for a perplexing piece of home technology. Is there anything else about your home computer, TV or appliances that makes you say, "Huh?"

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your question or let us know in the comments and we'll see if we can solve the mystery together!

Image: Taryn