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Spinning Magnet Question

  1. Oct 18, 2010 #1
    Lets say we have a spherical shaped and very powerful magnet. Lets say it has a 3" diameter and has some good weight to it.

    What would happen if you spun the magnet at great speeds. Lets say for the sake of argument say some 300,000 RPM.

    Could the centrifugal for created by the spinning actually alter the magnetic field any? I would assume would stretch it out along its equator? Or would it increase the force of the magnetic field, not actually "stretching it"?
  2. jcsd
  3. Oct 18, 2010 #2
    If and i mean a big IF u were able to spin a magnet that fast and was really powerfull ( only two i know are neoden. and coblalt/sal. they would cumble under the centrivical force of trying to spin that fast and/separate compisition so i guess the first question would be what kind of magnet would hold up to that ?
  4. Oct 18, 2010 #3
    Not sure about permanent or electromagnets.

    But if you spin an electrically charged metal object, the magnetic field should get stronger the faster you spin it - in this case, the effect is relativistic, meaning the magnetic field will depend on your motion relative to the object.
  5. Oct 18, 2010 #4
    Lets assume for a moment the spinning problem has been resolved. No issues of the system or the magnet being unstable. Thats more of a mechanical problem, but I am not really interested in that. Anyhow this is more of a theoretical question. I dont know of any reason this would actually be implemented. More or less looking at the physics behind it.

    I was also thinking, since we believe that gravity propagates at the speed of light, I would assume a magnetic field does as well? If so, and the magnetic field does change from centrifugal force, what would happen if we spun the magnet as the speed of light, possibly being able to bend light as gravitational fields can but on a smaller scale if there is some change in the field from spinning.
  6. Oct 18, 2010 #5
    The really interesting theoretical spinning-magnet problem is a strong solenoid magnet spinning about an axis that is perpendicular to the axis of the solenoid at a speed such that the solenoid field at a large radial distance sweeps azimuthally at a relativistic speed. Would this alter the magnetic field?

    Bob S
  7. Oct 18, 2010 #6
    One thing to look at is spinning black holes and spinning neutron stars. They got very strong magnetic field around them and they spin at relativistic speeds tangentially.

    Additional topics to look for are Active Galactic Nuclei (AGN) and galactic jets.
  8. Oct 19, 2010 #7
    Does the sweeping non-axial magnetic field from a rapidly spinning neutron star radiate electromagnetic energy?

    Bob S
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