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Homework Help: Question regarding Atomic Structure (orbits)

  1. May 19, 2005 #1
    I have my doubt,solution and question in the attachment that followed.Thanks for anybody that spend some time on this question.

    Attached Files:

  2. jcsd
  3. May 19, 2005 #2


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    Staff: Mentor

    It's only a coincidence that you got the right number for part (a). The fact that using the same procedure for part (b) gives the wrong answer, is a good indicator that you are using the wrong procedure.

    Your problem is that you are calculating [itex]1 / \lambda[/itex] which is not a number of revolutions. It's simply the reciprocal of the wavelength, with units of 1/meters. The answer you need doesn't have any units; it's just a "counting" number.

    I suggest that you look in your textbook for equations related to the speed [itex]v[/itex] of the electron in an orbit with quantum number [itex]n[/itex], and the radius [itex]r[/itex] of that orbit. If you know those quantities, you can calculate the time the electron takes for one orbit (the period, [itex]T[/itex]), and from that, the number of orbits it makes in [itex]10^{-8}[/itex] seconds.
  4. May 19, 2005 #3
    Ok first of all, calculate the wavelength emitted , in the same way you have calculated in your doc-attachment.then calculate the velocity of the electron in n=2 , i hope you can do that.
    then v= (frequency) (wavelength)
    calculate frequency with the above formula , this will be give you cycles /sec

    Now you want cycles in [itex]10^-8[/itex] seconds , use unitary method.I am getting the correct answer.
  5. May 20, 2005 #4
    Yes your both are right and I admit that I just have the 'luck' getting the first answer right and not the second.Thanks for your both detail explaination,jtbell and Dr.Brain,I really appreciate it.
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