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Magnetic fields such as a field from a neodymium magnet?

  1. Feb 21, 2009 #1
    Is there a material that blocks or reflects magnetic fields such as a field from a neodymium magnet?
     
    Last edited: Feb 21, 2009
  2. jcsd
  3. Feb 22, 2009 #2

    Vanadium 50

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    Re: Magnetism

    No. The best you can do is to move the field lines away from one area and towards another.
     
  4. Feb 22, 2009 #3

    LURCH

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    Re: Magnetism

    Right; magnetic shielding is usualy done with iron, which doesn't really "shield" in the conventional sense. Instead, it causes the magnetic field to concetrate where the iron is, thus greatly weakening the field strength beyond that bit of iron.
     
  5. Feb 22, 2009 #4

    Dale

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    Re: Magnetism

    Iron or mu metal (sp?)
     
  6. Feb 22, 2009 #5

    Vanadium 50

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    Re: Magnetism

    It is spelled "mu metal", but it doesn't block or reflect. All it can do is move field lines from one place to another, like Lurch describes.
     
  7. Feb 22, 2009 #6

    Gokul43201

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    Re: Magnetism

    Do you have a specific problem that you wish to apply this to?
     
  8. Feb 22, 2009 #7

    Dale

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    Re: Magnetism

    In the construction of passively shielded MRI suites we call it a shielding material. On one side of the shielding you may have a field of several tesla and on the other side a field of several nanotesla. So to me it seems fair to call that "blocking" the field.

    Obviously reflecting is the wrong word, since that refers to a wave behavior. But to me "blocking" seems close enough to "shielding".
     
  9. Feb 22, 2009 #8
    Re: Magnetism

    Are you saying you've been able to knock an MRI down to nT with mu metal? May I ask how?
     
  10. Feb 22, 2009 #9

    Dale

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    Re: Magnetism

    I have never seen it done with mu metal (too expensive), only iron. But it is pretty simple. Put the MRI in the middle of the room, and then place several hundred tons of iron in the walls ceiling and floor. Outside the room the field is very small.
     
  11. Feb 22, 2009 #10
    Re: Magnetism

    I am wanting to use a neodynium magnet to make a traffic light change when i pass over the trigger in the road with my motorcycle but I figured if the magnet is too strong it has to be doing something to the motor or electrical circutry on the motorcycle. So I thought that I would try to shield it somehow using an iron or some kind of material to either block or reflect the magnetic fields. From what people are saying though it sounds like a good reflection or any at all is near impossible or too much work/money.
     
  12. Feb 22, 2009 #11

    Dale

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    Last edited by a moderator: Apr 24, 2017
  13. Feb 22, 2009 #12
    Last edited by a moderator: Apr 24, 2017
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