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Homework Help: [Electromagnetics] E-Fields & Equipotential Surfaces

  1. Apr 2, 2017 #1
    1. The problem statement, all variables and given/known data
    This is from the book Engineering Electromagnetics by Hayt & Buck.


    2. Relevant equations
    E = - (ΔV/ΔL)

    3. The attempt at a solution
    At part (a), I took the potential difference between point A and the point directly above at the higher surface (106 V) and plugged in the needed values:
    E = - (106-104 V)/(2-Ay mm) = - 1000 V/m which is ≠ -1075-Ay V/m.

    Were there things that I have overlooked?
  2. jcsd
  3. Apr 2, 2017 #2


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    You overlooked that the 102 V equipotential is closer than 2 mm to the 104 V equipotential. You will get a higher magnitude for E if you take that into account.
  4. Apr 2, 2017 #3
    I think I'm kinda lost.
    So do I have to include the potentials from point A with respect to ALL equipotential surfaces? (i.e. 106-104 V, 108-104 V, etc.)? And with respect to the 102-V surface, is the coordinate of the point below point A relevant? If so, how do I get its coordinate?
  5. Apr 3, 2017 #4


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    Your calculation give an average value somewhere between the two ep lines considered.
    Maybe drawing an V(y) graph will make it clearer?
    Last edited: Apr 3, 2017
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