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Homework Help: Electric field magnitude problem

  1. Nov 10, 2009 #1
    There are three concentric thin spheres of radii a,b, c (a>b>c). The outer surface charge densities of their surfaces are σ, -σ and σ respectively. Find the magnitude of electric field at r (distance from centre) such that a>r>b ??

    My answer was,

    Er = [ K σ . 4 (pi) c2 / r2 - K σ . 4 (pi) b2 / r2 ]

    But the answer is given as,

    4(pi) b2 / r2
  2. jcsd
  3. Nov 10, 2009 #2


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    Homework Helper

    If 1/K=epsilon, I think your answer is correct.
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