(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A charge of +2q is placed at the origin and a second charge of –q is placed at

x = 3.0 cm. Where can a third charge +Q be placed so that it experiences a zero

force?

I think I've found the solution, I just need someone to verify why the math is the way it is at the end.

1) The overall force acting on the the new charge must equal zero, therefore I set them equal to eachother:

k (2q x Q)/(r^2) = k (q x Q)/(r-0.03)^2

(r - 0.03)^2 = r^2 (2q x Q)/(q x Q)

(r - 0.03)^2 = 2r^2

r - 0.03 = +/- 1.414r

-0.03 = -2.414r

r = .0124

OR

-0.03 = 0.414r

r = -.072

So would this mean that the charge would be .012 metres to the right of the negative charge? (Assuming that -q is placed 3 cm to the right of +2q)

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# Homework Help: Charge Placement

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