WATCH: Some very bizarre things happen when you drop a magnet through a copper tube

Here’s something your kids will love: Some very strange things happen when you drop a magnet down a copper tube — almost as if some mysterious invisible force grabs hold of the object, slowly guiding it through.

It’s not mysterious at all, however. It’s just science.

Electric currents and magnetic fields are closely related. If you have one, you often have (or can create) the other. The braking effect that happens to the magnet at it travels down the tube is due to an eddy current. That’s an electrical current that forms in the copper in response to the magnetic field that generated by the moving magnet.

The eddy current then creates a magnetic field of its own, causing the two magnetic fields to overlap, thus slowing the magnet as it falls.


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  1. BobBarker

    October 16, 2013 at 9:12 pm

    $10 bucks says it goes straight to amusement park inventions <_<

  2. Aaron Logan

    October 16, 2013 at 10:04 pm

    There cannot be an electric field without a magnetic field and vice versa.

  3. Hoz Holla

    October 17, 2013 at 7:16 am

    Yeah, SCIENCE!

  4. Ian on the Hill

    October 17, 2013 at 7:47 am

    Just hope he didn’t do this in a GOP state – they’d burn him for witchcraft.

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  6. D Traver Adolphus (@proscriptus)

    October 17, 2013 at 5:11 pm

    You do want to be careful when playing around with a magnet like that, which can break kids’ fingers.

  7. S.F.E.R.A.

    October 17, 2013 at 6:07 pm

    the magnet power is next “green energy” source on earth …

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  9. Alexander Ryan Baggett

    October 18, 2013 at 1:20 am

    Why take something perfectly scientific and cool and try to turn it divisive and political?

  10. Robert McLaughlin

    October 18, 2013 at 4:06 am

    Where can I buy this! Take my money!

  11. sferrains

    October 18, 2013 at 8:12 am

    The key thing here, of course, is that copper itself is not magnetic. It is a great conductor. Similar effects would occur with silver for instance. The eddy currents induced in the copper, create their own magnetic field which tends to hold the magnet, resisting gravitational force.

  12. Gary Williamson

    October 18, 2013 at 3:15 pm

    if you dont know, yu shouldnt be asking..

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  14. POA

    October 18, 2013 at 4:33 pm

    Eddy current brakes have been used on electric cranes for decades to control the lowering speed of the hoist. Nothing new here.

  15. mr. science

    October 19, 2013 at 12:07 am

    Newcomb made AV record players for schools in the 50’s- while they ran synchronous motors, they still had an aluminum disc beneath the platter with a horseshoe magnet you could put around the disc to slow it down….

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  17. Taylor

    October 19, 2013 at 1:23 am

    I feel like this is the first step in creating that hoverboard I was promised in Back to the Future.

  18. Adlock Hungry

    October 19, 2013 at 3:48 am

    That’s already how electricity is generated. Something (falling water, steam, internal combustion engines, etc) spins a turbine, which then spins a whole lot of magnets, in a whole mess of copper (or other conductors), then we get electricity.

  19. Adlock Hungry

    October 19, 2013 at 4:04 am

    David, in spite of Gary’s snide remark, that’s actually a pretty good question. Most of us take them for granted and it seems so simple but magnetism and electricity can be difficult to understand, invisible as they are. Try this for starters (it’s sort of comprehensible) –

  20. S C

    October 19, 2013 at 4:58 am

    Agree. Notice the wooden table, no wristwatch, etc. That is no ordinary magnet…

  21. DNALC

    October 19, 2013 at 5:41 am

    that is the dumbest thing i’ve ever read.

  22. Joe Blow

    October 19, 2013 at 7:14 am

    Nothin new ? Then why have they not taken this property and developed it further.
    The applications seem too numerous to contemplate.

  23. Howard Gray

    October 20, 2013 at 5:14 am

    How do magnets really work? The common answer provided by modern science in reality boils down to a well educated guess. We know just enough to be able to do a few constructive as well as destructive things with magnets. But I can say for certain we are just tickling the surface of the unknown with regard to the vast potential power that could be harnessed from this yet to be fully understood phenomenon.

  24. Gene Schmidt

    October 20, 2013 at 5:24 pm

    lol I love how nobody got this joke! “Fuckin magnets, how do they work?” is a now famous line out of a very bad rap song called “miracles”. hahaha man.

  25. Art Jedi

    October 20, 2013 at 5:31 pm

    That’s a wonderful demo, A couple of questions… That copper tube has a very thick wall (expensive) and those rare earth magnets aren’t cheap. I know a lot of teachers would love to let their students do this. Would copper pipe with a much thinner wall from Home Depot work?

  26. Jason

    October 21, 2013 at 2:27 am

    I’m pretty sure David is making a comical reference to this horrible music video (@1:52) :

  27. Paul Brett

    October 21, 2013 at 10:07 am

    Some cultural references are being missed here methinks – look up ICP – Miracles.

  28. Bruce Lorenzana

    November 5, 2013 at 7:04 am

    I want to hang the copper horizontally from the ceiling, and place the magnet spinning in the center.

  29. Ron

    November 5, 2013 at 7:17 am

    Well this IS a political web page!…

  30. txguy70

    November 5, 2013 at 5:39 pm

    Sounds like a good experiment for you to conduct.

  31. NSG

    November 5, 2013 at 9:17 pm

    Wrong. You can have ferromagnetic material which is magnetic without an electric field. In fact, superconductors with a current through them by definition have no electric field because their resistance is zero. Also you have have a static electric field with no moving charges. This is an electric field with no magnetic fields. So… wrong, and wrong.

  32. John

    November 7, 2013 at 6:39 pm

    Except that the stats are completely wrong nor is there any evidence of the validity of his scale. You cannot really do a correlation on two groups. That is meaningless. Also, we do not know what his scale measures.

  33. John Saylor

    November 23, 2013 at 10:39 pm

    There was a company that tried to use this concept to create a free energy source around 15 yrs ago I believe. They were getting people to sign up to have them install these generators that were about the size of a central air unit at no cost to you for free electricity. They were at the time trying to get a patent on it. Well I guess they were shut down because I never heard anything from them again. The way I understand they would have made their money by collecting from local utility companies for the excess electricity created from the units. I know there are states that require utility companies to purchase excess electricity produced from customers. I figured they would get shut down. If everyone was allowed to have free utilities the utility companies would go broke. Can’t allow that to happen can they?

  34. mypressedword

    November 24, 2013 at 10:52 am

    That wasn’t “bizarre”.

  35. Suzanne Sutherland

    November 24, 2013 at 3:43 pm

    Hello. My name is Eddy Current.

  36. Matt

    November 25, 2013 at 7:10 am

    Correcting someone should be a means to benefit them with enlightenment, not belittle them. I am not a physicist nor do I know much of physics so I have no idea who is right, I do know, however that you’re response was unnecessarily aggressive and you should perhaps give more consideration to the consequences of your communication with others in the future.

  37. Potter

    November 26, 2013 at 3:49 am

    And yet, NSG, even in the cases of the “isolated” (without E-field) ferromagnetic magnetic field and the charge-created “isolated” (without B-fields) E-field, all it takes to transform, at least partially, either of these “isolated” fields into their EM counterpart (B into E, and E into B), is a change in the frame of reference. So, essentially, Aaron is correct… you cannot have an electric field without a magnetic field and vice-versa.

  38. Anil Garg

    November 26, 2013 at 6:44 pm

    While I agree that on surface it looks divisive but we imprisoned Galileo because he said earth is round. Religion was/is/will be one of the biggest hurdle to scientific progress.

  39. Kim

    December 31, 2013 at 1:22 pm

    It’s a neodymium magnet, not a typical iron magnet. I did this demo in my 9th grade physical science lass or years.

  40. Sandy Frederick Scribner

    August 27, 2014 at 2:49 pm

    the price of copper! Just give me the tube LOL

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