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Free electrons and intrinsic spin magnetic dipole moment orientation?

  1. Jul 27, 2014 #1
    Are there any experiments or theories about the relation between magnetic dipole moment orientation and velocity vector of free electrons?
     
  2. jcsd
  3. Jul 27, 2014 #2

    WannabeNewton

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    A free electron's dipole moment doesn't couple to its classical velocity for obvious reasons. For accelerating electrons see Thomas precession.
     
  4. Jul 27, 2014 #3
    Just to make it clear, I'm not talking about the magnitude but spin axis orientation, i.e. North-South magnetic pole orientation. So are you saying that a single free electron traveling in a straight line with constant velocity, in absence of any external magnetic and electric fields, can have its magnetic spin dipole moment oriented in any arbitrary direction? How is that obvious, has it been experimentally measured?


    I understand that only applies to bound electrons in atomic orbitals. In which case electron's magnetic spin dipole moment orientation will also be relative to proton's magnetic fields and magnetic fields of other electrons, so it doesn't really answer the question. Still relevant though, so do you know what is electron's spin axis orientation in a hydrogen atom?
     
  5. Jul 27, 2014 #4

    WannabeNewton

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    Yes this should be entirely obvious. It's no different from saying you can prepare a system of torque-free and force-free gyroscopes in arbitrary directions. If I'm in the inertial rest frame of such a gyroscope then I can rotate it around at whim so as to have it point in any arbitrary direction I choose and the gyroscope will stay oriented that way because it is free.

    Then you understand incorrectly. Did you even do what I asked and look up Thomas precession? You certainly do not yet know of its generality and where it actually comes from. There's no point in me explaining it when you have a wealth of resources online which can do so in depth.
     
  6. Jul 27, 2014 #5
    Has it been experimentally measured? Beside spin magnetic moment, there is one more magnetic field electrons have, as described by Biot-Savart law, which has precisely defined orientation relative to velocity vector. Do you have any reason to believe electron's spin magnetic moment does not interact with its Biot-Savart magnetic moment?


    I looked up and the article clearly states it is about spin-orbit relation, and that: - "it only occurs in curvilinear motion and therefore cannot be observed independently of some centripetal force causing the curvilinear motion". And it's only a correction, I'm asking about the actual value it is a correction to. Do you know what is electron's spin axis orientation in a hydrogen atom?
     
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