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Homework Help: Need help on probability amplitudes

  1. Feb 4, 2005 #1
    I have this problem:

    The total number of waves Nw in a box is somewhat uncertain beause of the way the amplitude falls off. For a region of size DeltaX, call the uncertainty in the number of waves DeltaNw.

    a.) Relate DeltaNw to the uncertainty principle in the wavelength Delta(lambda). Assuming DeltaNw is about +/- 1, write this relation as an uncertainty principle relating DeltaX and Delta(Lambda).

    I have no clue how to start this, but I do have this eqn from Feynman's lecture, which we're using.

    Delta(lambda)/lambda = 1/(N*m)

    where N = # of lines on the grating
    m = order of diffraction pattern.

    I don'tknow if this eqn. corresponds to this though.

    so I'll assume...

    Delta(lambda) = 1/(delta(Nw) ? Am I going about it the right way?
  2. jcsd
  3. Feb 4, 2005 #2


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    Staff Emeritus
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    Gold Member

    Is this equation dimensionally consistent ?

    Can you write out the given question exactly as it has been stated to you ? Are we talking about "matter waves" of a particle in some kind of potential box, or somthing else ?

    Also, some background will be useful. What has been covered so far ?
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