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Homework Help: Modern Physics

  1. Jan 31, 2009 #1
    1. The problem statement, all variables and given/known data

    A single electron with de Broglie wavelength [tex] \lambda[/tex] passes through a slit of width d = 2[tex]\lambda[/tex]. The electron can then strike a flourescent screen. What will be observed on the screen?

    a) A diffraction pattern
    b) A single flash has if the electron had moved in a straight line through the slit.
    c)A single flash that could occur anywhere on the screen.
    d)A single flash that would most likely occur where a corresponding diffraction pattern would have the highest intensity.

    2. Relevant equations

    3. The attempt at a solution

    Since there is only a single electron, I dont think we will get a diffraction pattern. So my answer is b.
  2. jcsd
  3. Jan 31, 2009 #2


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    Note that you have only (and correctly) ruled out choice (a).

    You'll need to think some more about this. It might help to think what would happen if the experiment is repeated many many times.
  4. Jan 31, 2009 #3
    Well what if the experiment is done only once.?

    If its done many times, answer is probably "d".
  5. Jan 31, 2009 #4


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    If the answer is (b), as you had answered, imagine doing the experiment many times. If you always get "a single flash as if the electron moved in a straight line", then for many electrons you would just get a lot of flashes in a straight line directly ahead of the slit.

    This contradicts what is actually observed for many electrons: a diffraction pattern. So the answer is not (b).
  6. Jan 31, 2009 #5
    Ok then D right?

    Thnx for replies.
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