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Two Charges, Find Spot of Zero Potential

  1. Mar 8, 2009 #1
    1. The problem statement, all variables and given/known data

    Charges of -q and +2q are fixed in place, with a distance d = 6.00 m between them. A dashed line is drawn through the negative charge, perpendicular to the line between the charges. On the dashed line, at a distance L from the negative charge, there is at least one spot where the total potential is zero. Find the distance L.
    http://edugen.wiley.com/edugen/courses/crs1507/art/qb/qu/c19/qu_19.62.gif

    2. Relevant equations

    Vtotal = kq1/r1 + kq2/r2

    3. The attempt at a solution

    Since i'm looking for when vtotal = 0 then -kq/r1 = k2q/r2

    I'm lost as to where to go from here, I can't figure out how to use the d=6m. Any help is appreciated!
     
  2. jcsd
  3. Mar 8, 2009 #2

    lanedance

    User Avatar
    Homework Helper

    so find r1 in terms of r2

    trhen make use fo the fact that r1, r2 & d make a right triangle
     
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