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Homework Help: Heeeeeelp me

  1. Mar 21, 2009 #1
    plzz,,,heeeeeelp me

    In a simple model of the hydrogen atom, the electron revolves in a circular orbit around the proton with a speed of 2.2*10^6.





    Determine the radius of the electron's orbit???
     
  2. jcsd
  3. Mar 21, 2009 #2

    danago

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    Re: plzz,,,heeeeeelp me

    Have you made an attempt? What are your thoughts on the problem?
     
  4. Mar 21, 2009 #3
    Re: plzz,,,heeeeeelp me

    I do not understand the problem
     
    Last edited: Mar 21, 2009
  5. Mar 21, 2009 #4

    danago

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    Re: plzz,,,heeeeeelp me

    What forces are present in this simple model, and how can you relate them to the circular orbit? (i.e. what is providing the centripetal force?)
     
  6. Mar 21, 2009 #5
    Re: plzz,,,heeeeeelp me

    :blushing:???
     
  7. Mar 21, 2009 #6
    Last edited by a moderator: Apr 24, 2017
  8. Mar 21, 2009 #7
    Re: plzz,,,heeeeeelp me

    V^2/a ???

    but l dont have (a) in my problem !!!!
     
  9. Mar 21, 2009 #8

    danago

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    Re: plzz,,,heeeeeelp me


    Where did v^2/a come from? Did you mean [tex]a_c=\frac{v^2}{r}[/tex]?
     
  10. Mar 21, 2009 #9
    Re: plzz,,,heeeeeelp me

    yes!!
     
  11. Mar 21, 2009 #10

    danago

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    Re: plzz,,,heeeeeelp me

    Ok. Since there is an acceleration, there must be a force, right?

    What could possibly be providing this force? In which direction will it act?
     
  12. Mar 21, 2009 #11
    Re: plzz,,,heeeeeelp me

    centripetal force

    the direction to the center
     
  13. Mar 21, 2009 #12

    danago

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    Re: plzz,,,heeeeeelp me

    Yea, there is a centripetal force, but what causes it to exist? For example, a car can travel in a circular path because of the friction between the tires and road surface.
     
  14. Mar 21, 2009 #13
    Re: plzz,,,heeeeeelp me

    i dont know
     
  15. Mar 21, 2009 #14
    Re: plzz,,,heeeeeelp me

    because of the acc. ??
     
  16. Mar 21, 2009 #15

    Mentallic

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    Re: plzz,,,heeeeeelp me

    What does the nucleus of the atom consist of? How are these sub-atomic particles in the nucleus different to the electron orbiting the nucleus?
     
  17. Mar 21, 2009 #16
    Re: plzz,,,heeeeeelp me

    What does the nucleus of the atom consist of? n+ p

    How are these sub-atomic particles in the nucleus different to the electron orbiting the nucleus? ........
     
  18. Mar 21, 2009 #17

    Mentallic

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    Re: plzz,,,heeeeeelp me

    Yes, there are neutrons and protons in the nucleus. Now, what is the electric charge of each particle? positive/neutral/negative?
     
  19. Mar 21, 2009 #18
    Re: plzz,,,heeeeeelp me

    p >>>>positive

    n>>>>>neutral
     
  20. Mar 21, 2009 #19

    Mentallic

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    Re: plzz,,,heeeeeelp me

    Yep, and the electron is negative.
    Ok, so how do electric charges interact? i.e. a positive and a negative electric charge will do what to each other?
     
  21. Mar 21, 2009 #20
    Re: plzz,,,heeeeeelp me

    Attract each other
     
  22. Mar 21, 2009 #21

    Mentallic

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    Re: plzz,,,heeeeeelp me

    Correct. Now can you see where the centripetal force is coming from in order to keep the electron in orbit?

    Re-answer:
     
  23. Mar 21, 2009 #22
    Re: plzz,,,heeeeeelp me

    ????????????????/
    protons
     
  24. Mar 21, 2009 #23
    Re: plzz,,,heeeeeelp me

    any body can help me ????????
     
  25. Mar 21, 2009 #24
    Re: plzz,,,heeeeeelp me

    Hint: Coulombs law
     
  26. Mar 21, 2009 #25

    Mentallic

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    Re: plzz,,,heeeeeelp me

    Err... The answer you've given me is like answering "what keeps the moon orbiting Earth" with "Earth".
    But since you've answered the question in parts, yet have been unsuccessful in laying it out into a sentence, then I'll throw it onto a platter for you: "The electrons orbit the nucleus of the atom because of the electrical attraction of the proton and electron due to their opposite charges"

    So now we know what is providing the centripetal force (The force that keeps the electron from flying off in a straight line as defined by newton's first law).

    Again, using the equation [tex]a_c=\frac{v^2}{r}[/tex]
    where ac= centripetal acceleration
    v=velocity
    r=radius of orbit

    Since you know the velocity, and want to find the radius of the electron's orbit, you'll need to find out what the centripetal acceleration is. Any idea how to obtain that? Hint: Newton's second law.
     
    Last edited: Mar 21, 2009
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