Two positive point charges q are placed on the y-axis at y = a and y = -a. A negative point charge -Q is located at some point on the +x-axis.
(a) In a free-body diagram, show the forces that act on the charge - Q.
(b) Find the x- and Y-component of the net force that the two positive charges exert on -Q. (Your answer should involve only k, q, Q a and the coordinate x of the third charge.)
(c) What is the net force on the charge - Q when it is at the origin (x = 0)?
(d) Graph the x-component of the net force on the charge -Q as a function of x for values of x between -4a and +4a.