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Origin of Magnetic Force

  1. Oct 9, 2006 #1
    If I have one magnet sitting on a table and I take another magnet and bring close to the first one it will move towards the magnet!
    This is amazing to me. My question is why does one magnet make another move toward or away from it? what is the origin of magnetic force.
    I think it has something to do with QED(thats why im posting in the quantum forum) -perhaps the exchange of virtual particles and hence momentum but I am not sure.
    Is there a simpler explanation? if not can someone elaborate on the virtual particle scenario if that is the correct one?

    thank you
  2. jcsd
  3. Oct 9, 2006 #2
    You are asking two different questions. The first question is "what makes the one magnet move?". That's electrostatic force. But since the electrons are moving, relativity makes the force into a magnetic force. That's all.

    The second question is "why does it move AWAY or TOWARD". I don't know the answer to that. I think that is where smarter people start using the acronym QED.
  4. Oct 9, 2006 #3


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    The electrons have electric charge (unexplained datum*). An explanation for the direction of motion that is effective at the scales of humanly accessible energies is that electrons moving one way generate a different current from electrons moving the other, and relativity as you said makes that into a magnetic force, but differently directed for the two cases.

    *There are proposed explanations for charge quantization, but I am not aware of any mainstream explanation for the existence of charge itself.
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