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Homework Help: Electrostatic induction - rod and sphere

  1. Aug 12, 2014 #1
    1. The problem statement, all variables and given/known data

    Hi all, need a little help on an electrostatic induction problem.

    A positively charged metal rod is brought near to a neutral metal sphere. What is the charge of the metal sphere and the rod when the positively charged rod touches the neutral sphere.

    2. Relevant equations


    3. The attempt at a solution

    I know that when the positively charged rod is near the sphere, there will be electrostatic induction. There will be charge redistribution on the metal sphere, negative charges will be on the side of the sphere that is closer to the rod and the positive charges will be on the other side of the sphere that is further away from the rod.

    I am not sure what will happen when the positively charged rod touches the metal sphere. My guess is the negative charges on the already polarized sphere will flow into the positively charged rod, neutralising the rod and leaving the sphere positively charged.

    will appreciate if someone can enlighten me on this. Thanks!
  2. jcsd
  3. Aug 12, 2014 #2

    Simon Bridge

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    Science Advisor
    Homework Helper

    ... that was a well reasoned "guess", well done ;)

    Induction is just charges being attracted and repelled.
    The negative charges that were attracted to the rod will flow onto it - unless there is some reason for them not to.
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