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Homework Help: Eigenfunction problem

  1. Oct 4, 2009 #1
    1. The problem statement, all variables and given/known data
    Consider a particle that moves in one dimension. Two of its normalized energy eigenfunctions are [tex]\varphi_1(x) [/tex] and [tex] \varphi_2(x)[/tex], with energy eigenvalues [tex] E_1[/tex] and [tex] E_2[/tex].

    At time t=0 the wave function for the particle is

    [tex]\phi[/tex]= [tex]c_1*\varphi_1+c_2*\varphi_2[/tex] and [tex] c_1[/tex] and [tex]c_2[/tex]

    a) The wave functions [tex] \phi(x,t)[/tex] , as a function of time , in terms of the given constants and initials condition.

    b) Find and reduce to the simplest possible form, an expression for the expectation value of the particle position, [tex] <x>=(\phi,x\phi) [/tex] , as a function , for the state [tex]\phi(x,t)[/tex] from part b.

    2. Relevant equations

    3. The attempt at a solution

    for part a, should i take the derivative of [tex]\phi[/tex] with respect to t?
  2. jcsd
  3. Oct 4, 2009 #2


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    Gold Member

    For part a you need to use the Schroedinger's equation to know how the state evolves as a function of time, but you need to know the potential the particle is in...does the problem specify a potential?
  4. Oct 5, 2009 #3
    No , they don't specify the value of the potential
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