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Does a solenoid wrapped around a magnet meet resistance?

  1. Jul 2, 2015 #1
    If a solenoid were wrapped around a bar magnet, and a charge were applied through the solenoid, would there be resistance?
  2. jcsd
  3. Jul 2, 2015 #2


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    I don't think you can 'apply a charge'. Do you mean that a electric current is passed through the solenoid?
  4. Jul 3, 2015 #3
    This is exactly the principle behind how speakers work. Either the solenoid or the magnet would be caused to move (depending on which is anchored more sturdily) due to the interaction of the resulting magnetic field. In a speaker, of course, it is the solenoid that moves and vibrates a cone with varying effects depending on the properties of the current passed through it.
  5. Jul 3, 2015 #4
    Ok, will the current encounter resistance as it moves the magnet?
  6. Jul 4, 2015 #5


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    Look at it from the point of view of conservation of energy.
  7. Jul 4, 2015 #6
    I'm not totally sure. I do know, however, that whatever force the charge carriers feel as a consequence of the magnetic field will be in a direction perpendicular to their velocity, so they will not be slowed down by the magnetic field itself. But they will be pushed to one side of the wire (see the Hall effect on wiki). It seems conceivable that there might be some added friction or something like that if all the charges are pushed into the wall of the wire, but I can't say anything definite about that.
  8. Jul 4, 2015 #7
  9. Jul 5, 2015 #8


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    Perhaps we should ask what do you mean by "resistance" in this case?

    If you want the magnet to do any work (including moving itself against air resistance or friction) then the energy to do that will have to come from somewhere (eg the power supply to the solenoid).
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