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Levitate a magnet in aluminum tube with electro-magnet assist?

  1. Sep 7, 2014 #1
    I have an aluminum tube with 1.25" ID and 2.25" OD. I drop a neodymium grade N50 magnet, 1" dia, 2" long into the tube and enjoy watching the magnet drift very slowly down the tube. Lenz's law in demonstration.

    The paramagnetism of aluminum allows the magnet-in-motion to induce eddy currents in the aluminum tube, which in turn produces magnetic fields in opposition to that of the magnet, thus slowing the magnet's descent.

    What if I added an electromagnet coil around the exterior of the aluminum tube, and I pulsed that coil with DC current, in one direction or else in the opposite direction?

    What if I did not pulse the current in the coil, but rather held it steady at some value?

    With the right combination of parameters, could I stop the descent of the magnet inside the aluminum tube altogether? Could I possibly cause the magnet to reverse direction and slowly rise?

    What would happen if I used a paramagnetic material (like an aluminum slug) rather than a neodymium magnet? Again, with the right parameters, could a levitate the slug within the aluminum tube?

    Would I perhaps need to use two separate side-by-side coils on the exterior of the aluminum tube, separated by a few centimeters, and could I then levitate something inside the tube in the space between the two coils?
  2. jcsd
  3. Sep 7, 2014 #2


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    Science Advisor
    Gold Member
    2017 Award

    hi there
    welcome to the forums :)

    lots of good questions
    and since you have the magnet and the aluminium tube, how about trying what you have asked and see what happens, then report back here with the results :smile:

    That would be a much better path to discovery --- rather than some one just giving you a bunch of answers :wink:

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