Chapter 17, Problem 63GP

Three point charges are arranged along the x axis. Charge q₁ = −4.50 nC is located at x = 0.200 m, and charge q₂ = +2.50 nC is at x = −0.300 m. A positive point charge q₃ is located at the origin.

1. (a) What must the value of q₃ be for the net force on this point charge to have magnitude 4.00 µN?
2. (b) What is the direction of the net force on q₃? (c) Where along the x axis can q₃ be placed and the net force on it be zero, other than the trivial answers of x = +∞ and x = −∞?