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Zero potential, 3 charges

  1. Apr 8, 2014 #1
    1. The problem statement, all variables and given/known data
    Let us have a square ABCD (D is in the topleft corner) of size 1 m. Let us have 3 point charges situated in points B, C and D. The charges are following QB=2C, QC=-1C and QD=5C. The task is to find (a) the points/plane where the electric potential is zero and (b) two points where the electric intensity is zero.


    2. Relevant equations
    ψ = (1/(4*pi*epsilon))* (Q1/r1+Q2/r2+Q3/r3)=0


    3. The attempt at a solution
    According to the equation mentioned above I obtain the following equation
    2/rB-1/rC+5/rD=0
    But now what? Is my current procedure OK?
     
    Last edited: Apr 8, 2014
  2. jcsd
  3. Apr 8, 2014 #2

    BvU

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    Your procedure is OK. If (a) asks for the points in the plane where the potential is zero, you can write it out in x and y and try to solve. Expect to end up rather close to C. in 3D it becomes a deformed sphere.
     
  4. Apr 9, 2014 #3
    How do I write it in x,y? And why in 3D, I should find the points in 2D not 3D.
    Any hint to (b)?
     
  5. Apr 9, 2014 #4
    Anyone?
     
  6. Apr 9, 2014 #5

    BvU

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    "I should find the points in 2D not 3D" Good thing you tell us, because it's nowherer in the original posting.

    If (x,y) is a point in the x,y plane, what is the expression for rB ?

    Wrt (b), does the problem ask for electric intensity, or does it ask for electric field strength ? If so, do you have a relevant equation available ?
     
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