Two point particles, each of charge Q₁, are located on the x axis at x = ± L. Another particle having charge Q₂ is now placed at the origin. 

(a) Show that the total force on charge Q₂ is zero. 

(b) Suppose Q₂ is now moved a very small distance away from the origin, along the x axis. What is the direction of the electric force on Q₂? 

(c) Based on your result in part (b), explain why the origin is, or is not, a point of stable equilibrium for Q₂.