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Homework Help: Calculate the voltage at a point

  1. Feb 26, 2013 #1
    1. The problem statement, all variables and given/known data
    Calculate the electric potential at (a) point P in the first figure, and (b) point M in the second.
    http://www.usi.edu/science/physics/pickett/206/5p3f1.jpg [Broken]

    2. Relevant equations

    V=[itex]\frac{q}{4\piεr}[/itex]
    E=[itex]\frac{q}{4\piεr^{2}}[/itex]

    3. The attempt at a solution
    I'm not sure if E is really necassaryt, but I wasn't sure how else to get the direction right. So I did the vector stuff with E and got
    [itex]\vec{E}[/itex]=<0,[itex]\frac{-q}{2\pi\epsilon(.75)a^{2}}[/itex]>

    Now I'm stuck and don't know how to get to voltage
     
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Feb 26, 2013 #2
    You don't need the electric field - just use the definition of V.
     
  4. Feb 26, 2013 #3
    Is it as easy as adding the two V's up?
    Like
    [itex]V_{1}[/itex]+[itex]V_{2}[/itex]=V
    So the answer would be
    V=[itex]\frac{q}{2\pi\epsilon a}[/itex]

    Does direction not matter?
     
  5. Feb 26, 2013 #4
    Yes, you just add them up.
    The potential is a scalar, not a vector, so it doesn't have a direction.
     
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