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B Electron Spin and current-induced magnetic fields

  1. May 12, 2017 #1

    I'm currently investigating magnetic fields/their cause. This has inevitably led me to learn all about electrons. Here I want to post my understanding on electron 'spin' so people can correct me if I'm wrong/help others get a better understanding.

    So I watched this YouTube video for research:

    From what I understand, 'electron spin' is not an actual spin, but which way an electron attracts/repels. Since electrons exist as quantum particle clouds (and in the video it describes electrons as infinitely small points at ~7:20) 'spin' isn't really a thing they do.

    Essentially half electrons attract one way and half attract the other. It doesn't matter which orientation they are being tested in: it will always be roughly 50/50.

    This leads onto a big question: in a wire where electrons travel, why does the magnetic field induced always go anticlockwise if the electron current is flowing towards you? Surely if quantum mechanics dictates a 50/50 on electron spin, wouldn't it be a 50/50 chance the magnetic field would spin the other way?

    Maybe there's an answer to this or maybe this is one of science's yet-to-be-answered questions. It would be useful to know why if possible though.
  2. jcsd
  3. May 13, 2017 #2


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    This is not a very accurate description. The spin is the electron angular momentum. The electron's magnetic dipole moment is proportional to its spin.

    The magnetic field of a wire that carries a current is not due to the spin of the electrons, it is due to their motion.
  4. May 13, 2017 #3


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    The magnetic field in a current-carrying wire is caused by the motion of the charges, not their spin. The full explanation delves into special relativity and gets very counter-intuitive though, so don't expect an easy answer if you're trying to find the fundamental reason that a magnetic field is created.
  5. May 13, 2017 #4
    Thanks for clearing that up for me- are there any good links for reading into this?
  6. May 14, 2017 #5


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