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.
(a) What must the value of q3 be for the net force on this point charge to have a magnitude of 4.00 µN?
(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 = -∞?