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Electron spin? how?

  1. Dec 21, 2013 #1
    how actually electron and protons spin? explain me whether this spinning could provide torque to the positive charges then it means electrons and protons keeps rotating under their electrostatic field?
     
  2. jcsd
  3. Dec 21, 2013 #2

    ChrisVer

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    electrons are fundamental particles until today, so you can't really see them as spinning balls in order to give them that spin. In fact it's impossible to give it to them that way, since it would need them to spin faster than the speed of light (you know their spins, you know their radius boundary, so you can calculate the corresponding speed v, to find v>c).
    under EM field, the spin itself spins around the Magnetic field...(spin transition)
     
  4. Dec 21, 2013 #3

    jedishrfu

    Staff: Mentor

    The electron doesn't spin in a Quantum Mechanical view but there is a component of its equation that resembles classical spin of an object and so its been named as such:

    http://en.wikipedia.org/wiki/Spin_(physics [Broken])
     
    Last edited by a moderator: May 6, 2017
  5. Dec 21, 2013 #4

    jtbell

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    They don't actually spin like a classical spinning ball, because they aren't actually little balls (or any other classical object). Nevertheless, they have "intrinsic angular momentum" which is a fundamental property like mass and charge. "Intrinsic angular momentum" is a mouthful to say all the time, so we say "spin" for short. This was probably an unfortunate choice because it confuses so many people. Nevertheless, this term is so deeply embedded in physics language that it's impossible to change now, so we have to live with it.
     
  6. Dec 21, 2013 #5
    so what causes magnetic dipole moment in a ferromagnets?
     
  7. Dec 21, 2013 #6

    Bill_K

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  8. Dec 21, 2013 #7
    i just couldnt understand the language of wiki so could u please help me out!
     
  9. Dec 21, 2013 #8
    how an electron cant have a spin because they have an angular momentum i.e spin angular momentum then why?
     
  10. Dec 21, 2013 #9

    Drakkith

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    Electrons usually pair up in their atomic and molecular orbitals. To do this, they have to have opposite spins (Typically called spin "up" and spin "down"). This cancels out the magnetic field from each of the electrons. But in certain materials, such as iron, one of the electrons isn't paired up, so nothing cancels its magnetic field. When this happens, the iron can become aligned so that the magnetic field of many of these electrons all add up and can generate a macroscopic magnetic field. This is where ferromagnetism comes from.

    In classical terms only spinning objects have angular momentum. That means that something must be spinning around an axis. However, for subatomic particles, this view is incorrect. For example, for an electron to be physically spinning around its axis fast enough to generate its magnetic field it would need to be spinning faster than the speed of light. Which is not possible. Instead it has intrinsic angular momentum, much like it has intrinsic mass, charge, etc.
     
  11. Dec 22, 2013 #10
    but actually i am saying can it be possible that the electrons through their spinning could provide a torque to the nearby particle like the protons or positive ions?
     
  12. Dec 22, 2013 #11

    Drakkith

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    I don't believe so.
     
  13. Dec 22, 2013 #12
    but how can spinning give rise to magnetism?explain me what is actually spin and how it give rise to magnetism i m little confused
     
  14. Dec 22, 2013 #13

    Drakkith

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    I've already explained what spin is. But I'm afraid I can't explain the magnetism part. It looks to me like the magnetic field arises from having intrinsic angular momentum, but I'm not sure.
     
  15. Dec 22, 2013 #14
    but spin how canspin be the cause of magnetism i am not able to find it yet anywhere
     
  16. Dec 22, 2013 #15
    antell me whether here the magnetic field produced by electronis its electrostatic field only due to its charge or its a kind of another!!
     
  17. Dec 22, 2013 #16
    This is actually a hugely quoted fallacy. If you use the relativistic expression for angular momentum there is a v < c for any R that gives the correct angular momentum. However v=c is really the only speed that makes sense, since you can't "slow down" an electrons spin, and I believe the radius you get by requiring J=hbar/2 is well over the experimental upper bound
     
  18. Dec 23, 2013 #17
    Sorry, to answer the OP: nobody really knows what spin is, but it acts like classical angular momentum in a lot of ways. That is, spin+angular momentum is conserved.

    Currents produce magnetic fields, so classically speaking any charged object with angular momentum will have a magnetic field associated with it. Quantum spin also produced a magnetic field, although it is twice as strong as you would expect classically. Again, there is no generally accepted explanation of what is actually happening, but quantum field theory models it with incredible accuracy
     
  19. Dec 23, 2013 #18
    is it true in saying that a proton attracts the other electron due to its magnetic field because so far we had known through relativity that magnetic field is nothing but the electrostatic field?
     
  20. Dec 23, 2013 #19

    Drakkith

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    No, the proton attracts the electron through its electric field. The magnetic and electric fields are combined into the Electromagnetic field, but it's still important to distinguish between which effect, electric or magnetic, is taking place.
     
  21. Dec 23, 2013 #20
    but on what account we can distinguish them both because both are due to the existence of their charges? according to me here electric and magnetic is although both same but given different names to avoid misconception in which we are presently suffering?
     
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