A charge of -3.35 nC and a charge of -7.00 nC are separated by a distance of 40.0 cm. Find the position at which a third charge of +7.10 nC can be placed so that the net electrostatic force on it is zero.

Answer 1

well, it is fairly obvious a positive charge between two negatives can be placed at a zero force.

Let x be where the 3.35nC charge is.

Then ...

k3.35*7.10/x^2=k&*7/(.4-x)^2

solve for x.