Assuming that the particle is the 3rd
particle, we know that it’s location must be beyond q2; it cannot be between q1
and q2 since both fields point the similar way in the between region (due to
attraction). Choosing an arbitrary value of 1 for L, we get
k q1 / d^2 = - k q2 / (d-1)^2
Rearranging to calculate for d:
(d-1)^2/d^2 = -q2/q1 = 0.4
d^2-2d+1 = 0.4d^2
0.6d^2-2d+1 = 0
d = 2.72075922005613
d = 0.612574113277207
We pick the value that is > q2 hence,
d = 2.72075922005613*L
d = 2.72*L
