I posted this on Snopes when this board was down, and didn’t get much of an answer there, so I thought I’d try my luck here.
I have heard that it’s a seriously dangerous thing to accidentally (or deliberately) turn on a microwave without having anything in there. Does anyone know:
Thanks for your help.
My Kenmore Elite microwave oven has the following warning in the Safety section: “Do not operate the microwave oven when empty. Operating the oven with no food, or food that is extremely low in moisture can cause fire, charring or sparking.”
No time limit is given, I would assume that sparking because of reflections within the oven by microwaves that haven’t been absorbed or attenuated by passing into, or through, food could happen immediately. Charring and fire would take some time to develop. But why play with fire? If you have small children who like to push buttons it might be wise to unplug the oven when it’s not in use.
I would have to assume that charring or a fire would make the oven so expensive to repair that a new one would be called for.
It certainly can damage an older microwave oven which still uses a glass-ended microwave tube. The glass melts or cracks, letting air into the vacuum tube. Modern ovens use ceramic which can stand much more abuse.
I don’t know if it’s dangerous. Who said it was?
Thanks for the replies so far.
It’s one of those things that I’d heard that I didn’t know whether to put in the mental box ‘Urban Legend’ or ‘genuine safety tip’.
In light of the replies, I wonder if this sort of warning applies to older microwaves only, or to all microwaves in obvious ways (such as a fire), rather than to some horrible effect that is dangerous but wouldn’t be immediately obvious (such as pouring deadly radiation throughout the kitchen, to use one example).
A microwave oven is just a magnetron and a box (and a control circuit that turns it on and off). The magnetron is a thing that spins around and makes radio waves. The best way I’ve heard it explained to a non-techie is that it’s kind of like how you blow air across a soda bottle and you generate a sound wave, only it’s done with electricity and it generates radio waves.
If there’s nothing inside the box, the radio waves bounce all around. Some of them are going to get reflected back into the magnetron, and worst case you could damage the magnetron and possibly cause your microwave oven to to an HCF (halt and catch fire). I can picture a scenario where this might cause your house to burn down, but I can’t picture any likely scenario where “deadly radiation” would be spread all around your kitchen.
Despite the fact that everyone refers to the microwaving of food as “nuking” it, the radiation involved is radio waves, not the much higher frequency alpha, beta, and gamma rays like you’d expect from nuclear stuff. “I’m gonna RADAR it” is much more accurate than “nuking” it.
I know I’ve seen a picture of a damaged magnetron on the web but a brief search didn’t find it. Here’s a good link about what can go wrong in your microwave though:
http://www.everist.org/special/mw_oven/
The link also lists things you can put in a microwave, like a CD, neon tube, etc. and the type of special effect (guaranteed to make you go ooh and aaah) that you’ll get from it, assuming of course that you aren’t one of the unlucky ones that damages your microwave in the process.
My Kenmore Elite oven that posts the warning I cited is less than one year old.