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Homework Help: Square of expectation value

  1. Feb 26, 2006 #1
    hi all

    can sombody show me the way I could get
    the square expectation value http://06.up.c-ar.net/03/fd4f.jpg for a particle in a box

    where the answer is given to us :
  2. jcsd
  3. Feb 26, 2006 #2


    User Avatar

    Staff: Mentor

    [tex]<x^2> = \int {\psi^*(x) x^2 \psi(x)dx}[/tex]

    For the limits of integration, use the positions of the ends of the box. Some books use a box with 0 < x < L, others use -L/2 < x < +L/2, with correspondingly different wavefunctions.
  4. Feb 27, 2006 #3
    Where psi is orthonormal.
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