microwave ovens

Grape Balls of Fire



Far be it from us to deride anyone’s childish fascination with blowing stuff up in a microwave—a foolhardy nerd rite of passage if ever there was one—and what better place to exhibit dangerous, potentially expensive shenanigans than YouTube? The experiment is simple. Take a seedless grape and slice it lengthwise, making sure (this part is important) not to cut all the way through, so you leave a little bit of skin connecting the two halves. Put it face-up in a microwave, and blam: fireworks!

So what the heck is going on in there? Grapes are chock-full of electrolyte, an ion-rich liquid (a.k.a. “grape juice”) that conducts electricity. Each grape-half serves as a reservoir of electrolyte, connected together by a thin, weakly conducting path (the skin). Microwaves cause the stray ions in the grape to travel back and forth very quickly between the two halves. As they do this, the current dumps excess energy into the skin bridge, which heats up to a high temperature and eventually bursts into flame. At this point, the traveling electrons arc through the flame and across the gap, ionizing the air to a plasma (which itself can conduct electricity) and creating the bright flashes you see.

And that notion about poisonous gas tainting your roommate’s Hot Pocket? Well, the guy’s talking about the ozone generated when the air inside the glass is ionized. “Poisonous” might be too a strong word in this scenario (a little ozone definitely won’t kill you), although high concentrations of ozone can oxidize lung tissue and have been known to cause asthma in urban inversion-bowls like L.A. and Mexico City.

Again, DON’T TRY THIS AT HOME. Microwave ovens + biological capacitors = bad news. —Martha Harbison.

Related:

Flight of the Pole Dancer

Shake, Shake Chinook

Crane Overboard!

Goodbye, Moto

Stick That Landing

Yao: Rejected!

Why a Car on Skis Only Jumps So Far

Dude, Where's My Downforce?

Breakin' Circuits: The Electric Boogaloo

Smelting in a Microwave

Our scientist zaps tin and silver, shatters glass, and arcs his oven to prove a point.

There is an entire subculture of people who derive pleasure from putting strange things in microwave ovens, things that microwave oven manufacturers would most strenuously suggest should not be put there. In the hands of these people, table grapes produce glowing plasmas, soap bars mutate into abominable soap monsters, and compact discs incandesce. As a scientist, I'm enthralled by such phenomena (particularly the grapes), but somehow I've always found the subject a bit unsatisfying: Cool, but what is it really good for?

[ Read Full Story ]



Download Our iPhone App

Stay up to date on the latest news of the future of science and technology from your iPhone with full articles, images and offline viewing



Grab the Tech Buyer's Guide iPhone App

Carry everything you need to make a smart buy on HDTVs, cameras and 14 other product categories right in your pocket



Follow Us On Twitter

Featuring every article from the magazine and website, plus links from around the Web. Also see our PopSci DIY feed



Become a Fan On Facebook

Share links with friends, comment on stories and more


February 2010: Renovating America

Innovative fixes for five of the country's biggest infrastructure messes, plus a look the quest to read the human mind, the LCD screen that might finally kill paper dead, and the world's scariest science.

Read the issue here.

Popular Science Photo Pool


Share your photos in the Pop Sci pool at www.flickr.com!