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Number say about the spin of a particle?

  1. Jun 8, 2009 #1
    What does the number say about the spin of a particle?

    Like for an quarks it's half, what does it mean by 1/2 spin?
  2. jcsd
  3. Jun 8, 2009 #2


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    Last edited by a moderator: May 4, 2017
  4. Jun 8, 2009 #3


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    Re: Spin

    The number like 1/2 is the magnitude of the maximum z component of the spin angular momentum in units of hbar. That is, (1/2)hbar would this magnitude in whatever units you use for hbar.
  5. Jun 8, 2009 #4


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    Re: Spin

    It means that the particle has an intrinsic angular momentum with magnitude

    [tex]|\vec S| = \sqrt {s(s+1)} \hbar =\sqrt{\frac{1}{2} \left(\frac{1}{2} + 1 \right)} \hbar[/tex]

    which works out to [itex]9.14 \times 10^{-35}[/itex] kg-m2/sec.
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