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Charged Particles Probem

  1. Sep 15, 2011 #1
    1. The problem statement, all variables and given/known data
    Identical isolated conducting spheres 1 and 2 have equal charges q and are
    separated by a distance r large compared to the diameters of the spheres. The electrostatic
    force acting on sphere 2 due to sphere 1 is 3.10-6N. Suppose now, that the third identical sphere 3, having an isolating handle, and initially electrically neutral, is touched first to the sphere 1, then to the sphere 2, and finally removed. Find the electrostatic force which will be acting on the sphere 2 after all these manipulations.

    2. Relevant equations
    Coulombs Law: Fe= Ke ((q1)(q2)/r^2)
    Gausses Law:E*A

    3. The attempt at a solution
    Wel, we know that q1=q2. That means that both particles are going to move away from each other. I have that q2 has Fe= 3*10^6. The part I don't understand what does Sphere 3 do to my Sphere 2? I know that distance between q1 and q2 is r= ((Keq1q2)/F2)^1/2. I am simply stuck on the part of Sphere 3. Anyone want to shed some light?
  2. jcsd
  3. Sep 15, 2011 #2


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    Homework Helper

    When the third sphere is brought in it shares charge with the one it touches, so the first charge will be reduced by a lot, as the third sphere was initially uncharged, while the second charge is not reduced by so much since the third sphere already has picked up some charge from the first sphere.
  4. Sep 15, 2011 #3
    Thank you so much for explaining this!
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