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home science filter: Why is my water is singing!
February 25, 2011 6:45 PM   Subscribe

I just microwaved a mug of water. And after about a minute it started making a loud humming noise, like what happens when you run a wet finger around a champagne glass. It sounded like there were aliens landing in my microwave. What happened?

I microwaved the cup of water for about two minutes, dumped it out because there was something in it, refilled it and microwaved it for about a minute and a half when it started humming. I don't know if the cup being hot to start might be a clue. The noise was pretty loud and lasted for several seconds. Do you know why it would do this? My microwave has never made this sound before, I don't think it was a machine noise.
posted by chocolatemilkshakes to Science & Nature (13 answers total)
 
be careful heating water in a microwave for that long. microwaves can superheat water (aka hotter than boiling temperature) enough to cause a serious burn (ie 3rd degree requiring skin graft) the sound may have been a result of that
posted by supermedusa at 6:51 PM on February 25, 2011


That's scary! But in my case, I let it sit for a few minutes, and it's really not very hot.
posted by chocolatemilkshakes at 6:55 PM on February 25, 2011


I would suspect boiling water under the cup started steaming and whistling.
posted by fontophilic at 6:57 PM on February 25, 2011


Superheating water makes it boiling hot without it looking like it's boiling hot. When disturbed in this state, it can violently erupt into your face.

I would bet the humming was caused by water boilng underneath the mug, thereby vibrating it. But boiling water in a microwave is not a great idea. Reheating a mug of tea or coffee, yeah, but they are not good for boiling.
posted by Camofrog at 6:58 PM on February 25, 2011 [1 favorite]


Camofrog: "Superheating water makes it boiling hot without it looking like it's boiling hot. When disturbed in this state, it can violently erupt into your face."

I believe I've read that this happens when the side of the container is so smooth that it doesn't introduce any opportunity for bubbles; therefore when disturbed, all the bubbles instantly form and explode.

I think if you suspect this may have happened you can take something long (a spatula?) and nudge the cup and see what happens.

Snopes says you can prevent this by leaving some non-metal object in the cup, like a stirring stick or small wooden spoon.
posted by IndigoRain at 7:08 PM on February 25, 2011


My microwave does this whenever it's dirty, regardless of what I'm microwaving. I assume it's the rotatey plate. Are you sure you were hearing a feature of the water or mug?
posted by you're a kitty! at 7:30 PM on February 25, 2011


Ok so I was making more hot cocoa, and It started making the nose in about 10 seconds. Watching the microwave I realized that when a certain wheel on the rotator rolled over a certain spot it made the noise, every time it went around. They must both have something on them so they are squeaking. Thanks for the contributions!

(Now I have to clean my microwave)
posted by chocolatemilkshakes at 8:54 PM on February 25, 2011 [1 favorite]


But boiling water in a microwave is not a great idea.

Tens of thousands of Brits, Aussies and Kiwis who microwave the water for their daily cuppas without incident says different.
posted by obiwanwasabi at 10:57 PM on February 25, 2011


Superheating water makes it boiling hot without it looking like it's boiling hot. When disturbed in this state, it can violently erupt into your face.


Did this. Not a recommended life experience. The superheated turned to steam as I removed it from the microwave and it exploded at me, but I didn't get burned because all the energy went into making steam. Cleaned and dried the cup! Scared the crap out of me, though. Now I only boil water on the stove.
posted by pmb at 11:13 PM on February 25, 2011 [1 favorite]


Tens of thousands of Brits, Aussies and Kiwis who microwave the water for their daily cuppas without incident says different.

Actually this sort of problem is why every single British household has an electric kettle.
posted by citands at 12:10 AM on February 26, 2011 [4 favorites]


Electric kettle at our place in Aus. Pretty sure we've had one for longer than we've owned a microwave.
posted by titanium_geek at 2:07 AM on February 26, 2011 [1 favorite]


Yeah, we have 240v power, so kettle all the way. Mine boils in less than a minute, and I have had superheated water spit on me and so will never use a microwave for that purpose again - I like my hands and forearms too much. Or is obiwanwasabi being sarcastic? I can't tell anymore.
posted by goo at 2:16 AM on February 26, 2011 [1 favorite]


Superheated water isn't a big danger if you don't just grab the cup out of the microwave immediately. I made tea this way for years, but rather than remove the cup I'd just sort of toss the tea bag in; in occasional cases when the water was superheated, it'd boil up around the tea bag and out of the cup for a few seconds, but it never hurt me.
posted by you're a kitty! at 7:56 AM on February 26, 2011


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