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What determines an amplitude of a wave particle?

  1. Sep 15, 2013 #1
    According to Bohr's model, photon is emitted when electron "falls" to the lower level with energy equal to the difference between energies on these levels. This determines the frequency of the photon.

    What determines an amplitude of a wave created by a single photon, or electron?
    Last edited: Sep 15, 2013
  2. jcsd
  3. Sep 15, 2013 #2


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    Staff: Mentor

    In general, the amplitude of the wave function is related to the probability of finding the particle at various locations. More specifically the probability density is ##P(x) = |\Psi|^2 = \Psi^*\Psi## where ##\Psi^*## is the complex conjugate of ##\Psi##.
  4. Sep 15, 2013 #3
    Yes, but then how can I find the probability density without knowing an amplitude of the wave function?

    I mean, probability density and amplitude depends on each other, so if one side is unknown (amplitude in this case), then the other side also can not be determined
  5. Sep 15, 2013 #4


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    Staff: Mentor

    You don't. First you find the wave function by solving Schrödinger's equation for the situation that you are interested in, then you use the wave function to find the probability density.
  6. Sep 15, 2013 #5
  7. Sep 15, 2013 #6
    Sorry, I am still a bit confused.

    by this:

    You mean I should express ψ(x) from the time independent Schrödinger equation (attached)

    substituting values for E, m, h etc (assume I want to calculate amplitude, for defined energy, mass)


    Then how would I do that? I will always stay with the second derivative of the function and the function itself

    Would appreciate if you can give some links on solving Schrödinger equation for this kind of cases

    Attached Files:

  8. Sep 15, 2013 #7
    Schrodinger's equation is a partial differential equation

    Most of the time, it isn't easy (or just impossible) to find an exact solution, but there are about 5 or so instructive problems that are solved exactly in any Quantum mechanics textbook (e.g. Hydrogen atom, harmonic oscillator, etc...).

    If you're interested in learning to solve it, I recommend you brush up on your calculus first, then study some quantum mechanics.
  9. Sep 16, 2013 #8


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    Staff: Mentor

    Many students get their first taste of solving Schrödinger's equation in an "introductory modern physics" course using a textbook such as the ones by Beiser, Tipler, etc.

    Almost everyone starts with the "particle in a box" a.k.a. "infinite square well." A Google search should turn up a lot of web pages and university lecture notes.

    The version of the SE that you showed is the one for the hydrogen atom. Don't tackle that one until you've done a couple of simpler examples first.
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