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Adding Spins

  1. May 7, 2009 #1
    I am reading the section in Griffiths' Quantum about adding spins together. It says if you have a particle of spin s1 and another of spin s2 then the possible composite spins are

    s1+s2, s1+s2 -1, s1+s2-2, ... |s1-s2|

    that rule (though not proven in this text) has seemed straight forward to me until now. I have a particle of spin 1/2 and a particle of spin 3/2, so I get

    5/2, 3/2 ... but then the situation of them aligning antiparallel 3/2-1/2 = 1 does not occur as one of the integer steps, so do I include it as a possibility? It seems strange that the anti parallel arrangement should not be a possibility.

    Thanks for the help


    3/2+1/2 = 2 not 2.5

    One day I will figure out how to add those fractions together
    Last edited: May 7, 2009
  2. jcsd
  3. May 7, 2009 #2

    George Jones

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  4. May 7, 2009 #3
    That is a very good question. Thank you
  5. May 7, 2009 #4
    Am I banned for asking that? I understand if so
  6. May 7, 2009 #5


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    We all make these obvious mistakes sometimes. Don't worry about it. ;)
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