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Homework Help: Find wavelength

  1. Jul 31, 2011 #1
    1. The problem statement, all variables and given/known data
    Monochromatic radiation of specific wavelength is incident on H-atom in ground state. H-atom absorbs energy and emit subsequently radiations of six different wavelength. Find wavelength of the incident radiation.
    (a)9.75 nm
    (b)50 nm
    (c)85.5 nm

    2. Relevant equations

    3. The attempt at a solution
    I cancelled out hc on both the sides but then got stuck. I don't understand what to do next?
  2. jcsd
  3. Jul 31, 2011 #2
    Use the Rydberg formula.
  4. Jul 31, 2011 #3
    How can i use the Rydberg formula here?
  5. Jul 31, 2011 #4
    Well, it's an H atom, right? So the wavelengths it can absorb and the wavelengths it can emit are determined by the Rydberg formula.

    Suppose I gave you an H atom in the n=3 state. How many different wavelengths could it emit on its way back to n=1?

    By the way, I think the original question is a little unclear. I don't think it is intended to imply that a SINGLE H atom emits six different wavelengths. I think what is meant is that if you illuminate a lot of H atoms with the incident wavelength (or illuminate one atom many many times) and look at everything that comes out, you will see six different wavelengths.
  6. Jul 31, 2011 #5
    I get three different wavelengths.
  7. Jul 31, 2011 #6
    Right. So, what state would the H atom have to go into to subsequently emit 6 different wavelengths?
  8. Jul 31, 2011 #7
    Is it 4?
  9. Jul 31, 2011 #8
    I have found my answer, sorry for the disturbance. :smile:
  10. Aug 2, 2011 #9
    A side question here, If I have an atom that is not hydrogenic, how do I find this wavelength?

  11. Aug 2, 2011 #10
    It's very, very hard. Like quantum mechanics and supercomputers hard.
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