Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: De Broglies standing wave

  1. Jul 23, 2011 #1
    1. The problem statement, all variables and given/known data

    de Broglies standing wave condition demands that an inegral number of wavelengths fit into the circumference of the Bohr orbit. How many "interal wavelengths" are there in the fourth exited state of Be3+?

    2. Relevant equations

    n lambda = 2 pi r

    3. The attempt at a solution

    i tried to solve using the equation above but was confused on lambda and r, both unknowns.

    n = 5 because of fourth excited state i think
    not sure what use the charge is in this problem...
  2. jcsd
  3. Jul 29, 2011 #2


    User Avatar
    Homework Helper

    It seems to me the question is asking for the number of wavelengths, not a value/size of each wavelength. You had answered that. Perhaps I misread, or there was more to the question than you wrote ??
  4. Jul 29, 2011 #3
    Yeah, I think you just answered your own question. As you said, there are 5 internal wave-lengths.
  5. Aug 15, 2011 #4
    but i just used one piece of info and totally disregarded the rest and didnt use any formulas...
  6. Aug 15, 2011 #5


    User Avatar
    Homework Helper

    As I said, the [part of the] question you posted did not include any information which you feel you have "totally disregarded" ???

    EDIT: And don't get hung up on always wanting to use a formula.
  7. Aug 16, 2011 #6
    I didnt use Be3+ or any of the information of the circumference. I just came to n=5 due to fourth excited state.
    wouldn't that be disregarding the other pieces of information?
  8. Aug 16, 2011 #7


    User Avatar
    Homework Helper

    If the question had said:

    "How many "interal wavelengths" are there in the fourth exited state"

    people may be wondering "How many "fourth exited state of what?"

    I think the use of Be3+ is just there because some atom had to be.
  9. Aug 17, 2011 #8
    Wow than this was a much simpler problem than i thought it would be
    Thanks Guys
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook