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Physics problems driving me crazy- each book has different formulas

  1. Apr 25, 2013 #1
    1. The problem statement, all variables and given/known data
    The electric potential difference between two parallel metal plates is delta V. The plates are separated by a distance of 3 .0 mm and the electric field between the plats is E = 250 V / m. Calculate delta V

    2. Relevant equations

    E = - delta V / delta D

    3. The attempt at a solution

    250 V / m = - 120 V / D

    D = -0.75 V

    The answer says 0.75 V.

    Is it positive or negative? can someone help?

    The prior question I solved, using this formula and plugging in values gave me -1.2 * 10^3 N/C.

    So, why is it positive? Thanks
  2. jcsd
  3. Apr 25, 2013 #2


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    Homework Helper

    "Electric field between the plates" does not specify the direction of the field. It points to the lower potential. Calculate with the absolute values. A distance is always positive.

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