Two particles are separated by a distance d, Particle A has charge +Q and Particle B has charge +3Q. At what distance from particle A along the line connecting particles A and B would you place a third charged particle such that no net electrostatic force acts on it ?
F = kq1q2 / r^2
The Attempt at a Solution
Since there is no net electrostatic force on the third particle, the force from Particle A to C, and force from Particle B to C must be equal.
So I set up the equation
k(Q) / x^2 = k(3Q) / (d-x)^2
and solved for x using the quadratic formula.
x = .366d
However, the answer is d/9, which is x = .111d
Can anyone help me ? Thank you