1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Determine the radius of the electron's orbit.

  1. Dec 18, 2007 #1
    In one model of the hydrogen atom, the electron revolves in a circular orbit around the proton with a speed of 4.6 106 m/s

    f = mv^2/r

    F is the force of attraction between the electron and proton
    m is the mass of the electron
    v is the velocity it spins at
    r is the radius

    (9.11)(1.67*10^-27)K/r^2=[(1.67*10^-27)((4.6*10^6)^2)]/r

    when i solve for r, it is not correct, can you tell me if it is setup right

    thanks
     
  2. jcsd
  3. Dec 18, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    I don't understand what those numbers are. What's the mass of the electron? The charge on the electron and proton?
     
  4. Dec 18, 2007 #3
    The 1.67*10^6 should be 9.109 × 10-31

    On the left i am trying to find the force of attraction, is this the wrong way to go about this problem?
     
  5. Dec 18, 2007 #4

    Doc Al

    User Avatar

    Staff: Mentor

    Your approach is probably correct, but you're messing up some of the numbers. Start by writing your equation just in terms of symbols. Once we agree that the equation is correct, then you can plug in numbers.
     
  6. Dec 18, 2007 #5
    q1q2k/r^2 = mv^2/r
     
  7. Dec 18, 2007 #6

    Doc Al

    User Avatar

    Staff: Mentor

    Good. Now solve that for r before plugging numbers in.
     
  8. Dec 18, 2007 #7
    r = q1q2k/(mv^2)
     
  9. Dec 18, 2007 #8

    Doc Al

    User Avatar

    Staff: Mentor

    Good. Now plug away!
     
  10. Dec 18, 2007 #9
    9.11x10^-31*1.6x10^-19*8.99x10^9/(9.11x10^-31*(4.6x10^6)^2)
     
  11. Dec 18, 2007 #10

    Doc Al

    User Avatar

    Staff: Mentor

    Why do you have the electron mass here?
     
  12. Dec 18, 2007 #11
    I must have a number wrong, when I plug it
     
  13. Dec 18, 2007 #12
    1.6x10^-19*1.6x10^-19*8.99x10^9/(9.11x10^-31*(4.6x10^6)^2)

    That should be better, I used the mass instead of the charge.
     
  14. Dec 18, 2007 #13
    1.194e-11

    Got it, again, thanks for your help. Wish I had you as my teacher in school.
     
  15. Dec 18, 2007 #14

    Doc Al

    User Avatar

    Staff: Mentor

    Much better.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?