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Quantum Mechanics Expectation

  1. Jun 16, 2010 #1
    Quantum Mechanics "Expectation"

    1. The problem statement, all variables and given/known data
    1. Calculate the expectation value [tex]<p_{x}>[/tex] of the momentum of a particle trapped in a one-dimensional box.
    2. Find the expectation value <x> of the position of a particle trapped in a box L wide.


    2. Relevant equations
    [tex]\psi _{n}=\sqrt{\frac{2}{L}}sin \frac{n\pi x}{L}[/tex]
    [tex]<p_{x}>=\int \psi^*p_{x}\psi dx[/tex]
    [tex]<x>=\int \psi^*x\psi dx[/tex]


    3. The attempt at a solution
    I got confused on choosing the limits for both the problems for integrating them. What's the limits I should chose for both the problems.
     
    Last edited: Jun 16, 2010
  2. jcsd
  3. Jun 16, 2010 #2

    Doc Al

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    Staff: Mentor

    Re: Quantum Mechanics "Expectation"

    Where is Ψ non-zero? (What are the boundaries of the box?)
     
  4. Jun 16, 2010 #3
    Re: Quantum Mechanics "Expectation"

    x=0 and x=L
     
  5. Jun 16, 2010 #4
    Re: Quantum Mechanics "Expectation"

    Thanks I got it. The limits that I have to use are x=0 and x=L
     
  6. Jun 16, 2010 #5

    Doc Al

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    Staff: Mentor

    Re: Quantum Mechanics "Expectation"

    Exactly. :wink:
     
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