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Homework Help: Can someone teach me for this?

  1. Jan 9, 2010 #1
    Figure 1 shows part of an energy level diagram for a hydrogen atom.

    n=4 ------ -0.85eV
    n=3 ------ -1.50eV
    n=2 ------ -3.40eV
    n=1 ------ -13.60eV

    When an electron of energy 12.1eV collides with the atom, photons of three different energies are emitted.
    [a] on Figure 1 show with arrows the transitions responsible for these photons.

    > ????

    Calculate the wavelength of the photon with the smallest energy. Give your answer to an appropriate number of significant figures.

    >(E = hcl入)
    >energy in joules = (??) x 1.6 x 10^-19 = (????)(J)
  2. jcsd
  3. Jan 9, 2010 #2


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    I think this should be in the homework forum. Someone will probably move it for you. (Whoever does can delete this post)
  4. Jan 9, 2010 #3
    Hi, this is not my homework, im revising Physics at the moment, im stuck with this question.
  5. Jan 9, 2010 #4
    I've forgot most of atomic physics. But I can show u the process.
    [a]at first n=1,then comes the electron with 12.1eV,so the energy raises from -13.6 to -1.5,and n=3.Energy always wants to go from the high level to the low level,and at this time we have 3 ways,that is 3->2,2->1,3->1,these are the "photons of three different energies"
    then is easy
  6. Jan 9, 2010 #5

    ↓ .......↓

    Is it kindda look like this......?:confused:
  7. Jan 10, 2010 #6
    I'm sorry I wasn't here.
    But I can't catch your point.
    What I said means,at first n=1,after 12.1eV comes,n=3. n=3 has 3 ways to go as following
    goto 2,releasing 1.9eV
    goto 1,releasing 12.1eV
    but after 3 go to 2,we still have a 2,and this 2 can goto 1,releasing 10.2eV
  8. Jan 10, 2010 #7


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    Alright, I'm super confused by this point. To the OP: can you upload figure 1? Where are the arrows?
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