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Everything has ferromagnetic properties (?)

  1. Jul 9, 2011 #1
    Is it true that every material can be attracted by a magnetic field provided that the magnetic field is STRONG enough?
  2. jcsd
  3. Jul 11, 2011 #2
    Actually I was asking about a table that describes how magnetic the material is in numbers. (how is it called? 'coefficient of magnetism'?? or what?)

    Something like:
    sulfur | 0.0000000000145
    phosphorus | 0.0000000346
    and so on :D
  4. Jul 11, 2011 #3
    Try magnetic susceptibility. This is the quantity that may be what you need, for materials with weak magnetism:
    - paramagnetic - weakly attracted by a strong magnet
    - diamagnetic - weakly repelled

    For ferromagnetic materials the susceptibility or permeability may give some information.

    So no, not any material is attracted. It may be repelled.
    And when is weakly attracted does not mean it is ferromagnetic.
  5. Jul 12, 2011 #4
    Hmmm... As an extreme example: copper is an element known as a great magnetic "insulator", but if a strong enough magnetic field would be applied - would it be repelled or attracted?
    (And how strong a magnetic field must be in order to affect it just as strong as two magnets interact? (e.g. for comparison: how much times stronger than neodymium magnet?))

    PS: Actually now that I checked it out I see that copper is diamagnetc (it would be repelled - right?) - so only that other question remains: how strong a magnetic field must be to interact with it as strong as two magnets would?
    Last edited: Jul 12, 2011
  6. Jul 12, 2011 #5
    This is a very vague question. Even for a more specific one (given the expected force, the size and shape of material) it would be nontrivial.
    My guess though is that it will be higher than anything you can reasonably produce, at least for copper. Besides, the force on a induced dipole depends on both field strength and gradient of the field.

    Note. Copper is not really a magnetic insulator. A static magnetic field will go through it. Try to put a sheet of copper between two magnets. The main effect in reducing attraction will be the increase in separation due to the thickness of the copper.
    A copper sheet or box may provide good insulation against variable electromagnetic fields and/or static electric fields.
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