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Length Contraction of Electrons

  1. Nov 11, 2014 #1
    If you have a still wire with electrons moving through it, to an outside observer at rest relative to the wire, would the space between the electrons contract? I would think that special relativity causes the electrons to contract, (not the space between them) but the contracting of the electrons would cause the electrons to come closer together.
     
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  3. Nov 11, 2014 #2

    Nugatory

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    Electrons are point particles whose length is zero, so there's nothing to contract. The way to get the electrons to move closer together is for you, the observer, to be in motion relative to the wire; that will contract the length between them.
     
  4. Nov 11, 2014 #3

    A.T.

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    They have electric fields, which are contracted when the electron moves.
    Which would increase their mutual repulsion, if the electrons (their E-fields) weren't contracted as well.
     
  5. Nov 11, 2014 #4
    Exactly, and if the repulsions between the electrons contract, wouldn't that allow them to become closer together?
     
  6. Nov 11, 2014 #5

    Doug Huffman

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    Electron drift velocity (q.v.) in wire is on the order of millimeters per second.
     
  7. Nov 11, 2014 #6

    A.T.

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    It allows them to be closer together in the observers frame than in the electrons frame, while the repulsive force is the same.

    That's a
    misleading way to put it. Contracted repulsive fields are still repulsive, and don't bring anything together.
     
  8. Nov 11, 2014 #7

    Nugatory

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    That is true, which makes it all the more remarkable that the effects of the tiny relativistic length contraction of the distance between them is sufficient to explain the appearance of magnetic effects. See, for example, http://physics.weber.edu/schroeder/mrr/MRRhandout.pdf
     
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