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How Do 'Singing Magnets' Work?
dpbsmith asks: "Singing magnets are available at all of the usual geek-toy emporia, and, for all I know, ordinary toy emporia as well. They consist of a pair of magnets made of a polished substance with the general appearance of hematite. What is surprising, pleasing, and unexpected is that when the magnets strike each other under their own power, they produce a sharp, loud buzz that rises in pitch. The sound lasts a good fraction of a second and climbs somewhere into what sounds like the 200-500 Hz range. The exact sound and its duration are somewhat unpredictable and depend on how the magnets happen to strike each other. It is a little like the sound that you get when you mash a pingpong ball against a pingpong table with a paddle. What physics are involved in the production of these sounds?"
"Google searches turn up some forum postings that indicate that it is a synthetic magnetic substance similar to hematite that's available cheaply in China as an industrial byproduct. The singing magnets are a little larger than size of olives; the shape is similar to a (U. S.) football but slightly more elongated. Their major axis is about 5 cm long, their minor about 1 cm. They are fairly powerful and will jump together when placed on a desk about three inches apart. They can distort the colors on a CRT display from a distance of over 20 cm.
Contrary to expectation, the poles of the magnets are oriented along one of the minor axes of the ellipsoid, not the major axis.
Neodymium magnets in 'ordinary' shapes produce boring 'plinks' when they snap together. Something about the shape of these magnets makes the sound much longer-lasting and entertaining. It is not simply the bounding rebound of two objects made of stiff-but-elastic material. Transfers of linear to angular momentum are clearly involved.
If course, I'd love to know whether these things were 'invented' or 'discovered', and by whom, trying to do what.
Contrary to expectation, the poles of the magnets are oriented along one of the minor axes of the ellipsoid, not the major axis.
Neodymium magnets in 'ordinary' shapes produce boring 'plinks' when they snap together. Something about the shape of these magnets makes the sound much longer-lasting and entertaining. It is not simply the bounding rebound of two objects made of stiff-but-elastic material. Transfers of linear to angular momentum are clearly involved.
If course, I'd love to know whether these things were 'invented' or 'discovered', and by whom, trying to do what.
What physics are involved in the production of these sounds?
flubber!
Monday, March 04, 2002. Eric was just wondering how the singing magnets work, but not finding any satisfying explanation on Google and Wikipedia, he decided to finish one of the emails he was just writing. It seemed like a good idea to not think about science for a while and concentrate on something else.
Eric paused, breathing heavily. He'd never done this before and he wanted to make sure all of his best qualities were included in this email.
Eric wondered if this woman he had found on match.com would be impressed with his talents. He decided to put more detail into the message.
Eric pondered for a moment, wringing out his soaked handkerchief, and continued with his typing.
Chewing on his tongue and squinting, Eric pushed his mind into overdrive and produced a beauty of a riddle on the spot:
Pleased with his linguistic talents, undoubtedly matched by no one, Eric then asked his potential love-conquest:
Eric exhaled slowly and rubbed his belly. It was growling and no doubt wanted its nightly bottle of Jägermeister. He decided to finish up the email in anticipation of the coming alcoholic stupor.
Eric wondered how to wrap up the email, something that would hook the lady on him and make her want more...