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Magnetic flux

  1. Mar 23, 2013 #1
    Maybe a stupid question, but I'm trying to get my brain around the concept of magnetism, specifically for static magnets, not electromagnets. I understand that the magnetic field is a result of all the moments in the atoms being aligned. The spin of the electrons around the atoms is the current so to speak. But I fail to see how this field transmits, is it some type of particle? Is there some form of medium needed? or is this some type of space time distortion like gravity? And how is it that a metal object will attract regardless of its orientation? Surely the random alignment of the atoms will result in a zero net force?
     
  2. jcsd
  3. Mar 23, 2013 #2

    mfb

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    In quantum field theory, this is a possible description, but it is not useful if you want to consider regular magnets.
    No.
    No (at least not in a significant amount).
    The magnetic field is just a field in space - every point in space has a vector "magnetic field at that point".
    The spins in the other object get (partially) aligned due to the external field.
     
  4. Mar 23, 2013 #3

    rude man

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    Iron and a few other metals exhibit paramagnetism. In these metals, electrons spinning about their own axes will align in the presence of an external B field to form a surface current (internally, the currents cancel). Each electron acts like a miniature magnet so they align just like compass needles. This surface current then sets up a B field in the normal manner.

    A small part of the B field is due to the electrons revolving about their nuclei but most of these "Amperian currents" are due to electron spin.

    These currents are not moving conduction currents & encounter no resistance, so they go on forever, theoretically! (Once the external field is removed they will mostly revert into random orientations. However, some residual magnetism makes them weak permanent magnets. Some materials retain a lot of the spin so they become strong permanent magnets.

    Bottom line: same B field, set up by electric currents just like by a wire or coil..
     
  5. Mar 24, 2013 #4
    Ok thank that makes it more clear, so in essence, it's a property of space time, if every point in space time has a magnetic vector associated with it, that sounds like extra dimensions in space time? So particles could be described in terms of position (and derived forms like speed, acceleration) orientation (in terms of moment), and magnetic field vector?
     
  6. Mar 24, 2013 #5

    mfb

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    No.
    Magnetic field is a property of the space, not of the particles. Charged particles influence the magnetic field in the space around them.
     
  7. Mar 24, 2013 #6
    Ok thanks, understood, I was just under the impression that force was transmitted only by way of particles. So does that mean that space has a moment? Such that the difference in the two moments, particle vs space, causes the magnetic force? Which suggests space has spin itself? Sorry if these come across as futile questions... Please bear with me
     
  8. Mar 24, 2013 #7

    mfb

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    That is not true.
    Do you mean momentum? Electromagnetic fields have momentum, indeed.
    ??
     
  9. Mar 24, 2013 #8
    As in spin, does space have spin? Such that electrons tend to want to spin in the same direction? Or what you are saying is that the magnetic field is on top of and additional to space, like a membrane that exists in space?
     
  10. Mar 24, 2013 #9

    mfb

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    No.
    No.
    Yes.
    No.
     
  11. Mar 24, 2013 #10
    I suppose its pointless trying understand it by way of metaphor...
     
  12. Mar 25, 2013 #11
    Sorry, I just have a naive view, in that i just see things in terms of Newton's third law, objects travel along a straight line and everything that goes along with that, and Eisenstein's general relativity in which states that straight lines are not always straight in that a property of matter (the higgs boson?) can bend them into loops. Entropy suggests that everything reduces to its lowest state of energy, so to me everything is then a combination of these three fundamentals. It's apparent now that there is more to the story... Additional things like the magnetic field that can distort or offset these...
     
  13. Mar 25, 2013 #12

    mfb

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    Who is Eisenstein?
    No, that is not related to the Higgs boson.
    It does not.
    It is not.
     
  14. Mar 25, 2013 #13
    Eisenstein is a typo, between me and my iPad I'm getting everything wrong! Lol... I suppose entropy is more like the ambient state of energy... Something like thermodynamics ... So that things tend toward the most abundant state of energy... None the less I am now officially off topic... Thanks for the help...
     
  15. Mar 25, 2013 #14
    So it's a "solenoidal" vector field, by the maxwell equations, this is twist and spin, but no divergence at any point in the field... A gradient that integrates to 0... But is not 0 itself... Bizarre concept... Interesting... Almost as if two opposing forces apply to every point...
     
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