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When is electric field zero and electric potential non zero

  1. Jan 13, 2013 #1
    1. The problem statement, all variables and given/known data

    Which one of the following statements about electric field strength and electric potential is
    incorrect?
    A Electric potential is a scalar quantity.
    B Electric field strength is a vector quantity.
    C Electric potential is zero whenever the electric field strength is zero.
    D The potential gradient is proportional to the electric field strength.


    2. Relevant equations

    E=K Q/(R^2)
    V=K Q/R

    K=1/(4∏ε)

    3. The attempt at a solution

    The answer is C

    If for example you had two positive charges of 3 coulombs a distance 4m apart.
    The electrostatic field at the midpoint would be zero. Effectively a positive charge at this point would be push by an equal force in both directions.

    However the Electric potential V would be 2*(k*(3/4)

    So you can have a zero E with a non zero V

    Is this logic ok
    Thanks for any help
     
  2. jcsd
  3. Jan 13, 2013 #2

    CAF123

    User Avatar
    Gold Member


    The electrical potential goes as 1/r, but your reasoning is correct. You could also consider the electric potential and electric fields associated with spherical conductors: Provided the conductor is closed, the E field inside is 0 but the potential is a constant.
     
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