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Bohr Model Problem (Part 2 - Updated)

  1. Jun 13, 2014 #1


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    Greetings again,

    So I realize my last thread: https://www.physicsforums.com/showthread.php?t=757685 became chaotic with my thoughts and un-clear writing.

    I've re-did the work to make it easier for people to understand my thought process. The two questions are as follows:

    7)Calculate the wavelength that corresponds to an emission of energy of 1.977x10^-19 J.

    8)If the initial energy level for the energy change in problem seven is n = 7, what is the final energy level?

    And here's my updated work:


    Any confirmation if I followed the right steps and achieved the correct answer?

    Thank you as always,
  2. jcsd
  3. Jun 14, 2014 #2

    Simon Bridge

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    OK for 7.
    For 8, you do not need, and should not, recalculate ΔE from the wavelength.
    You already know what ΔE is, it was given to you at the start.

    You should have an equation for the energy levels for Hydrogen in terms of n.
    What is it?

    ΔE=Ef-Ei = E(nf)-E(ni)

    So what is nf and ni?
  4. Jun 16, 2014 #3


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    Well, n initial is giving to us at n level = 7.
    n final is what we are calculating and I received the answer of 1.

    Nf = 1 is incorrect?
  5. Jun 17, 2014 #4

    Simon Bridge

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    Dunno - I did not do the problem, and I would have chosen a different approach.
    You asked if you'd done the right steps - there are no right steps, but there are more efficient approaches. Full marks usually comes from demonstrating understanding.

    Want to check your answer, try doing it another way.
    Work out the equation for ΔE in terms of E1 and both n's - then solve for nf, and then plug the numbers in.

    Remember: you are training to solve problems that nobody knows the correct answers to.
    You need to work out, now, some ways to tell if you are right or not.
  6. Jun 17, 2014 #5


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    Simon - Cheers for the response. Allow me some time to get back to this (hopefully tomorrow morning). I appreciate your responses greatly.
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