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B Magnetic field of a circular electromagnet?

  1. May 13, 2018 #1
    I know that the poles of an electromagnet that is straight is at the ends but what if the metal core is an iron ring?
     
  2. jcsd
  3. May 13, 2018 #2

    mfb

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    Then you have a circular magnetic field. This is called a toroid magnet, and you'll find it in various particle detectors, fusion reactors and probably a couple of other places.
     
  4. May 14, 2018 #3
    Would the poles be perpendicular to the ring's plane?
     
  5. May 14, 2018 #4

    mfb

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    There are no magnet poles in this case.
     
  6. May 14, 2018 #5

    jtbell

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    Hints: what does it mean for part of a magnet or electromagnet to be a "pole"? Does that condition hold for any part of a toroid?
     
  7. May 15, 2018 #6
    It would mean that it could attract/repel other magnets right?

    Would such a toroid electromagnet be able to repel or attract though? I had this idea of where I could make two of these toroid electromagnets repel and attract each other perpendicular to their plane, if that's possible.
     
  8. May 15, 2018 #7

    mfb

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    Outside you have a bit of stray field, which can lead to a weak force. Inside the field is quite homogeneous, so you don't have a net force. You can have torque - the magnet trying to align itself with the magnetic field.
     
  9. May 15, 2018 #8

    jtbell

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    And what is it about the magnetic field configuration (near the poles) that causes it to attract/repel other magnets? To keep things simple, suppose the "other magnets" are small (in physical size) compared to the magnet in question.

    Also, by "attract" I don't mean just that the "other magnets" rotate to align themselves with the field. I mean that there is a net force which attracts them to or repels them from the magnet in question.
     
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