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Electromagnetic Repulsion Power

  1. Feb 6, 2015 #1
    So I coiled ~3' of 28awg wire in a 1/4" coil and connected it to an AA battery. It is unable to pick up nuts but still attracts and repulses in the presence of a permanent magnet. When a piece of iron is added to the center of the coil the strength of the magnet increases, as expected, and it is now able to pick up nuts. The problem is that now both poles of the permanent magnet are now attracted to the iron core. How can I achieve repulsion with the electromagnet? Would more turns or voltage help?

    Thanks for your help!
     
  2. jcsd
  3. Feb 6, 2015 #2

    davenn

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    Hi
    and welcome to PF :)

    yes many more turns and a few more volts....
    At the moment the magnetic attraction of the permanent magnet to the iron core far exceeds the magnetic field strength of your electro magnet

    cheers
    Dave[/QUOTE]
     
    Last edited by a moderator: Feb 6, 2015
  4. Feb 6, 2015 #3

    sophiecentaur

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    The permanent magnet is obviously a lot stronger than your electromagnet so the induced magnetisation in the iron, due to the permanent magnet - and which will cause attraction, is stronger than any magnetisation that your electromagnet can produce. So the net resultant of the two magnets still causes attraction. If you could actually measure the forces involved, I am sure you would measure a smaller force with your electromagnet on 'repel' setting. You could use a small Force Meter or weak spring or you could even hang the iron on a string cradle and see if the angle it hangs at is altered with and without current flowing.
     
  5. Feb 6, 2015 #4
    That makes sense. But does this mean that the repulsion force will always have a lower magnitude than the attraction force?
     
  6. Feb 6, 2015 #5

    davenn

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    until you make the electromagnet stronger, yes
     
  7. Feb 6, 2015 #6
    Thanks for your help!
     
  8. Feb 7, 2015 #7

    sophiecentaur

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    The Iron is passive and will take a 'polarity' which is due to the stronger of the two fields. So you will always have a field vector that is a product of the cancellation of the two fields you put it in. The resultant will always be less in magnitude than either of the two.
    I don't think there is anything inherently asymmetrical about the situation you describe so your 'repulsion' term only means 'attraction' to the other (winning) magnet.
     
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