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Quick Magnet Question.

  1. May 28, 2012 #1
    If I have a cylindrical permanent magnet and an electromagnet with both poles facing each other, would the permanent magnet attract to the soft-iron core of the electromagnet? Assuming both magnets are restricted on an axis and have +/- equal strength (~375lb pull force, 2" cross sectional diameter).

    I would assume the electric current would temporary magnetize the soft-iron core, thus temporary eliminating its attraction force. But I am not sure.
  2. jcsd
  3. May 29, 2012 #2

    Simon Bridge

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    You should be able to discover the answer by experiment :)

    The iron core will, of course, be affected by the total magnetic field it is subject to wouldn't it?
  4. May 29, 2012 #3
    That's what i'm trying to find out. Also, I am short of equipment to perform an experiment. :(
  5. May 30, 2012 #4

    Simon Bridge

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    You just said you had an electromagnet and a permanent magnet - after that you just need a spring and a ruler.
  6. May 30, 2012 #5
    I said "If" I have a electromagnet and a permanent magnet...
  7. May 30, 2012 #6

    Simon Bridge

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    My mistake. Well, if they are not easy to get then you have bigger problems to take care of first :)

    Think of the core of the electromagnet as just a lump of iron ... don't let it's purpose distract you, that a human assignment not a physical one. The coil is an electromagnet whether it has a core or not.

    No matter where that lump of iron is, it will be affected by the total magnetic field there. Make sense?

    If the iron is inside the coil, then it is most affected by the coil's field ... this is not to say that it is not affected by the magnet's field. The effect may be so small wrt the coil that it can be neglected in the math though.

    The core question is wether a magnet interacts with a magnetic field only through it's own magnetism or if it also reacts as a lump of non-magnetic metal in addition. For instance, if you move a magnet towards a metal magnet, is there a current induced in the magnet(s) to oppose the motion?
  8. May 31, 2012 #7
    Force exerted on iron beetwen repelling magnet

    Force to an iron between 2 magnets
    Two magnets (A and B)has the same pulling energy @ 50 lbs. Put face by face on the same north poles (in repelling mode) within 10 mm distance. If a 3 mm bar iron strip/steel trip put in the middle of these 2 magnets, What will the forcstrip irone exerted on the strip iron/steel ? Howdo you calculate ?

    Best regards

    Windu Hernowo
  9. Jun 1, 2012 #8
    Re: Force exerted on iron beetwen repelling magnet

    I found a data Sheet for a 47.75lb magnet:
    (p.s. is there an equation are to how they got those numbers?)

    I have a question, if the iron strip is placed in the middle of the 2 magnets, would the total force of attraction be doubled that of the iron strip-magnet attraction force?
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