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Homework Help: Uncertainty question

  1. May 2, 2006 #1
    Consider the wavefunction: particle in an infinite well of width L, with
    wavefunction given as a superposition of two energy eigenstates, with quantum numbers n=1 and m=2. Show that the Energy-Time uncertainty principle, applied to the time it takes <x> to change by an
    amount σx, indeed holds true in this case.

    soo, i have <x> and σx, and i guess i can find σE by doing sqrt(<E>^2 + <E^2>), i just don't see how i'm supposed to use those values for the uncertainty principle which says ΔE*Δt< hbar/2.

  2. jcsd
  3. May 2, 2006 #2

    Tom Mattson

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    OK so you should have [itex]<x>[/itex] as some function of [itex]t[/itex], right? So set the problem up like this (insert the function of time you found in place of my [itex]f(t)[/itex]).


    [tex]<x>+\sigma x=f(t+\Delta t)[/tex]

    From there you are supposed to solve for [itex]\Delta t[/itex].
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