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Homework Help: Simple question regarding spin

  1. Dec 14, 2006 #1
    Simple question regarding spin :)

    1. The problem statement, all variables and given/known data

    An electron is in spin state (superposition of spin eigenstates) given by the wavefunction: [tex]\chi=\frac{1}{3}\chi_+ + \frac{2\sqrt{2}}{3}\chi_-[/tex]. I need to find the probabilities that a measurement would find the electron with spin up or spin down.

    2. Relevant equations

    Uh.. you just square the coefficients, right? :)

    3. The attempt at a solution

    Probably a silly question but this seems too easy. I don't have this as a formula anywhere in my notes or book.. but to find the probability of spin up, you just square (1/3), and to find the probability of spin down, it's just the square of 2sqrt(2)/3... right?
  2. jcsd
  3. Dec 14, 2006 #2


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    If it's properly normalized, that will do it.
  4. Dec 15, 2006 #3
    Thanks! :)
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