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Homework Help: Uniform, non-zero electric field

  1. Apr 11, 2010 #1
    1. The problem statement, all variables and given/known data

    At x = 1.00 m, the voltage is 4.00 V. At x = 3.00 m, the voltage is also 4.00 V. Assuming that there is a steady, uniform non-zero electric field over this entire region, give four possible directions of that electric field.


    2. Relevant equations

    E = (delta V)/d
    Ue = qV
    (the electric potential = charge * voltage)

    I'm not entirely sure, these are just the ones that sort of relate the electric field with voltage.


    3. The attempt at a solution

    For these charges to have an equal voltage in the electric field, the force of the electric field * the distance between either charge and one of the plates should = 0 (from the first equation above), so anywhere in the field where they are at the same y coordinate (in line with each other), they should have the same voltage. This gives me two directions for the field- it can point up or down (switching the positive and negative plates) and the voltages could be the same:

    - - - - - - - -
    ____________ <-- negative plate

    ^ ^ ^ ^ <---direction 1
    --(1m)----(3m)------------------->x axis
    ____________ <-- positive plate
    + + + + + + +

    and if you switch the negative and positive plates, the field points down, my second direction, but I don't see how you could have two additional directions, so perhaps I am thinking about this wrong. Any insight would be great! thanks
     
  2. jcsd
  3. Apr 12, 2010 #2

    tiny-tim

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    Hi A_lilah! :smile:

    (have a delta: ∆ :wink:)

    Hint: if a uniform electric field is North, where are the lines (or surfaces) of equal voltage (equal electric potental)? :smile:
     
  4. Apr 12, 2010 #3
    I'm not sure I understand what you mean by north~ do you mean pointing upwards? The equipotential lines are perpendicular to the electric field lines...
     
  5. Apr 12, 2010 #4

    tiny-tim

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    That's right. :smile:

    So …
    :wink:
     
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