Two Charges, Find Spot of Zero Potential

AI Thread Summary
To find the distance L where the total electric potential is zero between charges of -q and +2q, the equation Vtotal = kq1/r1 + kq2/r2 is used. Setting Vtotal to zero leads to the relationship -kq/r1 = k2q/r2. The challenge lies in expressing r1 in terms of r2 and incorporating the fixed distance d = 6.00 m between the charges. Utilizing the geometry of the situation, specifically the right triangle formed by r1, r2, and d, is essential for solving the problem. The discussion emphasizes the need for clarity in relating these distances to find the correct value of L.
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Homework Statement



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

Homework Equations



Vtotal = kq1/r1 + kq2/r2

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!
 
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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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