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I Probably a Dumb Question: How are E and (delta)V correlated?

  1. Feb 9, 2017 #1
    What I Think I Understand: ΔV = Ed (d being dstance) and that V = kq/r

    please correct me if I'm misunderstanding those.

    What I need to know: When E = 0, what happens to the electric potential? and vice versa.

    Me Working it out: So if i use the first equation up here, If E = 0, then electric Potential = 0. Even with the second equation wouldn't I compare the net electric field with the net potential at a point? If so, then my answer remains the same. Either my equations are wrong or i'm really misunderstanding a simple concept. I may just be reaching my burnout point with physics right now. (I'm a few days in of focused physics studying and I can't wrap my head around simple concepts like this anymore.)
     
  2. jcsd
  3. Feb 9, 2017 #2

    Doc Al

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    Staff: Mentor

    No; where E = 0 the change in electric potential = 0. (ΔV = 0)
     
  4. Feb 9, 2017 #3
    Then does that apply to just V as well? And thanks for the quick response! :)
     
  5. Feb 9, 2017 #4

    Doc Al

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    Staff: Mentor

    If I understand you correctly, no.
     
  6. Feb 9, 2017 #5

    Doc Al

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    Staff: Mentor

    That second equation describes the potential at some distance from a positive charge. (It assumes V = 0 when infinitely far from the charge.)
     
  7. Feb 9, 2017 #6
  8. Feb 10, 2017 #7
    The two equations that you gave are valid for two separate situations. ΔV = Ed is valid if the electric field is uniform. If it is not, then the relation is approximately valid only for short distances, and along a direction parallel to the field.
    The second equation, V = kq/r gives the potential of a point charge q at the origin. In this case, the electric field is not uniform, so your first equation ΔV = Ed is not correct.
    In all cases, the relation between electrostatic field and potential is: E = - ∇V. I typed E in bold to state that E is a vector.
     
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