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Homework Help: Very stuck on electrostatics question

  1. Apr 20, 2009 #1
    State Gauss' Law

    A spherical volume carries a uniform charge density [itex]\rho_0[/itex]. A particle of mass m and charge -q is placed inside the sphere at radial distance r. (This additional charge does not distort the field arising from the [itex]\rho_0[/itex] charge density.) Show that the particle oscillates harmonically and find its' oscillation frequency.

    don't really know what to do here.

    obviously gauss' law is [itex]\nabla \cdot \vec{E}=\frac{\rho_0}{\epsilon}[/itex]
    and the lorentz force will probably come into play, [itex]F=\int_V \rho_0 \vec{E} dV[/itex] seeing as ther's no magnetic field.

    but i can't put it together.

    thanks guys.
  2. jcsd
  3. Apr 20, 2009 #2


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    Homework Helper

    What is the equation of motion for a harmonic oscillator? Compare the equation of motion of a harmonic oscillator to the equation of motion you have for this given problem. It should strike you as very similar.
  4. Apr 20, 2009 #3
    yeah. just got it there actually. thanks though. took me flippin ages!
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