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A NONCONDUCTING sphere with uniform volume charge density ? HELP

  1. Jun 2, 2012 #1
    A NONCONDUCTING sphere with uniform volume charge density ? HELP!!

    1. The problem statement, all variables and given/known data
    so this is the problem,
    a nonconducting sphere of radius [itex]\alpha[/itex] has a uniform volume charge density with total charge Q. the sphere rotates about an axis through its center with constant angular velocity [itex]\varpi[/itex] . Find the magnetic field at the center of the sphere.

    ALSO, how is a non conducting sphere able to have charge density ?
     
  2. jcsd
  3. Jun 3, 2012 #2

    tiny-tim

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    Hi SoulofLoneWlf! :smile:
    Why not? It's con-conducting, so if we place charges anywhere inside it, they stay there! :biggrin:
    Show us what you've tried, and where you're stuck, and then we'll know how to help! :smile:
     
  4. Jun 3, 2012 #3
    Re: A NONCONDUCTING sphere with uniform volume charge density ? HELP!!

    Hello tiny time :)
    and thanks for clarifying the non conducting part ;)
    Well to be honest i don't know where to start i know i can find the e field by placing it inside a gaussian surface (bigger sphere) but that is really all i have which isn't really the scope of this problem i think ?
     
  5. Jun 3, 2012 #4

    tiny-tim

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    a stationary charge has no magnetic field

    a moving charge has a magnetic field

    what method can you use to sum the magnetic fields of all the charges? :wink:
     
  6. Jun 3, 2012 #5
    Re: A NONCONDUCTING sphere with uniform volume charge density ? HELP!!

    so then the magnetic moment of each charge would be usable?
    μ=Q/(2Mass)*[itex]\alpha[/itex]
     
  7. Jun 3, 2012 #6

    tiny-tim

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    "magnetic moment"? :confused:

    what is the magnetic field of a moving charge?​

    (and how can you split the sphere up so as to simplify the integration?)
     
  8. Jun 3, 2012 #7
    Re: A NONCONDUCTING sphere with uniform volume charge density ? HELP!!

    sorry i guess i took a wrong turn on this one but magnetic field of a moving charge would then be

    B=(μ_o/4∏)*(qv x [itex]\hat{r}[/itex])/r^2 ??
    and to simplify integration of a sphere consider it a circle? 0 to pie?
     
  9. Jun 3, 2012 #8

    tiny-tim

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    yes :smile:

    you can use cylindrical shells, or circles
     
  10. Jun 3, 2012 #9
    Re: A NONCONDUCTING sphere with uniform volume charge density ? HELP!!

    which approach would you recommend ? to use on this one? circles?
    by the way thank you for your help so far :)
     
  11. Jun 4, 2012 #10

    tiny-tim

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    (just got up :zzz:)

    makes very little difference

    try one and see what you get :smile:
     
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