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Homework Help: Physics sphere help

  1. Mar 6, 2005 #1
    Sphere A carries a net positive charge, and sphere B is neutral. They are placed near each other on an insulated table. Sphere B is briefly touched with a wire that is grounded. Why is Sphere B now negatively charged? I mean, why isn't it positively charged (which I though was the answer) or neutral? Is it the flow of electrons from A to B?

  2. jcsd
  3. Mar 7, 2005 #2


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    There is no way for charge to flow off sphere A. Grounding sphere B just allows charge to flow onto it from some unlimited source (the earth) until it is at 0 volts. In this case, the positive sphere pulls negative charge up from the ground onto sphere B.
  4. Mar 7, 2005 #3

    Dear friend,
    When we say that B is nuetral,it means that there are equal amount of +ve & -ve charge in B. When the sphere B is grounded,the +ve charge in A attracts the -ve charges to that side.The +ve charges and -ve charges are seperated.+ve charges will flow to ground making B a -vely charged body.This phenomenon is called Induction.
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