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Homework Help: Why is it safe to be insulated from ground while working with electric currents?

  1. Sep 14, 2008 #1
    1. The problem statement, all variables and given/known data
    From serway's book chapter 23(electric fields), questions section.

    2. Relevant equations


    3. The attempt at a solution
    The obvious answer would be that it is safe because the student holding the sphere is insulated from the ground, but what does that really mean ?
    If I try to imagine what might be happening on a microscopic scale, I would imagine the charged particles(be it -e or +e, or both, I don't know..) next to the point of contact flowing through the body as soon as they are exposed to the charged sphere, how would the charged particles in the body "know" whether the boy's feet are touching the ground or not..
    Now, if the two objects were metals, they I would expect such behaviour, since the e- in metals(solid state) are free to move around, so how come it is different for the body?
  2. jcsd
  3. Sep 14, 2008 #2


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    Homework Helper

    That's because the person who is holding the sphere is treated as a conductor. The charge doesn't have any path to the ground since the person is insulated by the stool, hence the current would not flow.

    I'll think of it as the person + sphere being at the same electric potential and if the bodies are equipotential, there is no electric field involved and hence no current flows. The ground is held at constant 0V potential, so any path to the ground would have a current flowing.
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