Eddies in the space-time continuum?
November 4, 2015 12:07 PM Subscribe
That hockey puck sized magnet looks scary. Like it could pull the iron out of your blood.
posted by bonobothegreat at 12:27 PM on November 4, 2015 [3 favorites]
posted by bonobothegreat at 12:27 PM on November 4, 2015 [3 favorites]
Why doesn't everyone learn about this in grade school....
Would have made Physics II in college a lot easier, all we ever did were vector calculus problems about magnets and wires, but it's really hard to imagine those in your head.
posted by miyabo at 12:31 PM on November 4, 2015
Would have made Physics II in college a lot easier, all we ever did were vector calculus problems about magnets and wires, but it's really hard to imagine those in your head.
posted by miyabo at 12:31 PM on November 4, 2015
I've been showing people this for years. If you use a 1m length of standard (UK) 15mm copper pipe and a small stack of 10mm disc magnets, and tweak the number of magnets in the stack, you can get it so that the magnets float down the pipe in a really leisurely way. You don't really need a massive chunk of copper like the one in the videos.
posted by pipeski at 12:35 PM on November 4, 2015 [1 favorite]
posted by pipeski at 12:35 PM on November 4, 2015 [1 favorite]
Yeah, that is an amazingly huge piece of copper pipe, and a hockey-puck sized neodymium magnet is amazingly dangerous. It could crush a finger in the wrong scenario.
posted by GuyZero at 12:39 PM on November 4, 2015
posted by GuyZero at 12:39 PM on November 4, 2015
Would have made Physics II in college a lot easier
As I recall, we did this, or something very similar in an EM lab in second year (wire through an electromagnet in our case, I think). And yeah, it's a good demo of the vector nature of fields. It's also basic motor theory.
posted by bonehead at 12:51 PM on November 4, 2015 [1 favorite]
As I recall, we did this, or something very similar in an EM lab in second year (wire through an electromagnet in our case, I think). And yeah, it's a good demo of the vector nature of fields. It's also basic motor theory.
posted by bonehead at 12:51 PM on November 4, 2015 [1 favorite]
I was wondering what the effect would be if you had a laminated stack of copper instead of a solid pipe.
More or less?
What if you had coils of wire like in a tesla coil?
posted by Just this guy, y'know at 12:54 PM on November 4, 2015
More or less?
What if you had coils of wire like in a tesla coil?
posted by Just this guy, y'know at 12:54 PM on November 4, 2015
Isn't this also the explanation for how hybrid cars use braking to recharge the battery?
posted by straight at 12:56 PM on November 4, 2015
posted by straight at 12:56 PM on November 4, 2015
A+ title. Is he?
posted by iotic at 1:01 PM on November 4, 2015 [4 favorites]
posted by iotic at 1:01 PM on November 4, 2015 [4 favorites]
Found in related links, the world's simplest electric train.
posted by JHarris at 1:01 PM on November 4, 2015 [6 favorites]
posted by JHarris at 1:01 PM on November 4, 2015 [6 favorites]
Another video describes how the "train" was made.
posted by JHarris at 1:05 PM on November 4, 2015 [1 favorite]
posted by JHarris at 1:05 PM on November 4, 2015 [1 favorite]
Is this something I'd need to own a hockey puck-sized rare earth magnet to understand?
jk Lenz's law is rad, science is rad
posted by a halcyon day at 1:09 PM on November 4, 2015
jk Lenz's law is rad, science is rad
posted by a halcyon day at 1:09 PM on November 4, 2015
pipeski: you can get it so that the magnets float down the pipe in a really leisurely way
Err, eponystericals are acceptable to mention if they're ones where it's pretty much inconceivable that the user could ever post something eponysterical, right?
posted by ambrosen at 1:14 PM on November 4, 2015 [4 favorites]
Err, eponystericals are acceptable to mention if they're ones where it's pretty much inconceivable that the user could ever post something eponysterical, right?
posted by ambrosen at 1:14 PM on November 4, 2015 [4 favorites]
I used neodymium magnets in a science fair project, and all I remember is that they look spooky when tumbling down a copper pipe. I don't think that's a good hypothesis.
posted by Turkey Glue at 1:19 PM on November 4, 2015 [1 favorite]
posted by Turkey Glue at 1:19 PM on November 4, 2015 [1 favorite]
This reminds me of the early days of Facebook, where one of these videos went around for a while.
posted by rhizome at 1:37 PM on November 4, 2015
posted by rhizome at 1:37 PM on November 4, 2015
This effect is exploited to great success in vibrationally damping scanning probe microscopes, such as those made by ScientaOmicron.
The copper 'fins' each surround a rare earth magnet which quenches small vibrations transmitted from the floor by generating eddy currents. This allows the whole instrument to remain steady while it scans over the surface to image and manipulate individual atoms!
posted by Pazzovizza at 1:43 PM on November 4, 2015 [3 favorites]
The copper 'fins' each surround a rare earth magnet which quenches small vibrations transmitted from the floor by generating eddy currents. This allows the whole instrument to remain steady while it scans over the surface to image and manipulate individual atoms!
posted by Pazzovizza at 1:43 PM on November 4, 2015 [3 favorites]
Just this guy, y'know: "I was wondering what the effect would be if you had a laminated stack of copper instead of a solid pipe.
More or less?"
The laminations would suppress eddy currents making the effect less. At least that's how it works in xfrmers and motors.
posted by Mitheral at 3:00 PM on November 4, 2015 [2 favorites]
More or less?"
The laminations would suppress eddy currents making the effect less. At least that's how it works in xfrmers and motors.
posted by Mitheral at 3:00 PM on November 4, 2015 [2 favorites]
If the copper is a bunch of insulated holed disks stacked around a plastic tube, the changing magnetic field would still induce currents in them. The currents would loop around in the plane of each disk.
If the copper is a bunch of insulated rod arrayed parallel to a plastic tube or plates fanning around the rod, the changing magnetic field wouldn't induce currents in each rod or plate.
posted by sebastienbailard at 3:13 PM on November 4, 2015 [2 favorites]
If the copper is a bunch of insulated rod arrayed parallel to a plastic tube or plates fanning around the rod, the changing magnetic field wouldn't induce currents in each rod or plate.
posted by sebastienbailard at 3:13 PM on November 4, 2015 [2 favorites]
True. I guess when I see lamination I think split lamination in which there isn't a continuous loop around the hole.
posted by Mitheral at 4:03 PM on November 4, 2015 [1 favorite]
posted by Mitheral at 4:03 PM on November 4, 2015 [1 favorite]
The magnetism augmented by cold, interesting. Space, cold but nevertheless attractive.
posted by Oyéah at 4:54 PM on November 4, 2015
posted by Oyéah at 4:54 PM on November 4, 2015
to replicate this at home is to take two smaller rare earth magnets glued or clamped to a holder, a rare earth magnet in ring or horseshoe form, then drop bits of thin aluminum sheet inside the magnetic field. A bit of cut up soda can is perfect.
Actually, you should be able to do it with just one magnet or stack of magnets. You can just slide the aluminum sheet past the field on a nearly vertical inclined plane.
You can also float bits of non-ferrous metal or anything else on water on a bit of foam and wave a strong magnet back and forth over the metal sample.
Ferrous, fully magnetic materials will attract. Paramagnetic materials will wobble to and fro with induced eddies, and diamagnetic materials (say, cryogenically cooled liquid oxygen) will usually be weakly opposed to magnetic fields.
Turns out nearly everything exhibits some response to magnets, not just ferrous metals like our old grade school textbooks insist on for simplicity.
posted by loquacious at 5:57 PM on November 4, 2015 [1 favorite]
Actually, you should be able to do it with just one magnet or stack of magnets. You can just slide the aluminum sheet past the field on a nearly vertical inclined plane.
You can also float bits of non-ferrous metal or anything else on water on a bit of foam and wave a strong magnet back and forth over the metal sample.
Ferrous, fully magnetic materials will attract. Paramagnetic materials will wobble to and fro with induced eddies, and diamagnetic materials (say, cryogenically cooled liquid oxygen) will usually be weakly opposed to magnetic fields.
Turns out nearly everything exhibits some response to magnets, not just ferrous metals like our old grade school textbooks insist on for simplicity.
posted by loquacious at 5:57 PM on November 4, 2015 [1 favorite]
Well, it would have to be some level of a conductor, if I am remembering correctly.
(And I was right even before reading the explanation, so yay me! My swarm of particle cannon picosats are not far off now, let me assure you!)
posted by Samizdata at 9:07 PM on November 4, 2015
(And I was right even before reading the explanation, so yay me! My swarm of particle cannon picosats are not far off now, let me assure you!)
posted by Samizdata at 9:07 PM on November 4, 2015
There's the classic physics demo, slotted pendulum and solid pendulum in magnetic fields.
posted by sebastienbailard at 10:22 PM on November 4, 2015
posted by sebastienbailard at 10:22 PM on November 4, 2015
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posted by SansPoint at 12:19 PM on November 4, 2015 [20 favorites]