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Homework Help: Electric potential and electric field

  1. Jun 27, 2009 #1
    Help on these problems-
    1. If there is a charge then it has its own electric field. Now infinity is the area outside the electric field. This means a charge outside the electric field i.e at infinity , will not have any effect due to that charge. But by the formula F = kQ/rsq , there should be some force on any charge because there is always a value of r.

    2. The electric potential at a point in an electric field is 100 V. How much work will have to be done to move an electron from that point to just outside the field?
    The problem is that if potential in the given question in 100 V. If 1 C charge is present then 100 J of work is done on what?
  2. jcsd
  3. Jun 27, 2009 #2


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    What have you tried thus far?
  4. Jun 27, 2009 #3


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    It makes no sense to say "at infinity" for any problem. It only makes sense to determine the force in the LIMIT as r-> infinity, that is what does the force tend to as you get further and further away.
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