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Homework Help: Quantum mechanics in atoms question

  1. Jul 5, 2004 #1
    The question is:
    A hydrogen atom absorbs a photon and makes a transition from a 3d level to a 4f level. What is the wavelength of the absorbed photon ?

    As i know 3d is n = 3, 4f is n = 4

    and wavelength = hc/delta E

    so the deltaE is E4 - E3 or E3 - E4 ??

    Last edited: Jul 5, 2004
  2. jcsd
  3. Jul 5, 2004 #2


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    Homework Helper

    I think that's right. You also need to know what the energy is (compared to ionization energy, for instance) at a given principle quantum number.
  4. Jul 6, 2004 #3
    Just use the absolute value of E4 - E3, because all you are interested in is the AMOUNT of energy needed to make the transition, which is a positive value. So it makes no difference if you use E4 - E3 or E3 - E4, since the absolute value produces the same result.

    Since this is hydrogen, then [tex]E_i = -13.6/n^2[/tex] (in eV).
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