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Homework Help: Angular Momentum of Electron

  1. Apr 30, 2010 #1
    1. The problem statement, all variables and given/known data

    What is the angular momentum of a hydrogen atom in (a) a 4p state and (b) a 5f state? Give your answers as a multiple of h-bar aka (h/2*pi)

    2. Relevant equations

    Radius of nth orbit = 5.29*10-11 * n^2
    Angular Momentum = mvr
    V of nth orbit = sqrt ( e^2 / (4*pi*epsilon_0*m*r) )

    3. The attempt at a solution

    For 4p orbit i plugged in 4 to the equations and got angular momentum is equal to 4 h-bar,
    not right however....
  2. jcsd
  3. Apr 30, 2010 #2
    Solved my own problem, if anyone has this same issue the answer is more simple than i thought. L = h-bar*sqrt(l(l+1)) where l is the orbital quantum number
  4. May 3, 2010 #3
    I tried plugging in 4 for the orbital quantum number and got it to be sqrt(20)*h-bar, but this was incorrect. Did I plug in the wrong number for the orbital?

  5. May 3, 2010 #4
    In the 4p state, n=4 and l=1. Where 'l' comes from the p in 4p. Remember the quantum number 'l' is labeled by s,p,d,f... for l=0,1,2,3,..

    You don't use the 'n' when solving for the angular momentum.
  6. May 3, 2010 #5
    Ok, ya I forgot how to find l. Now it works. Thanks for the response
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