Updated: Aug 2
a) In below picture the negative charges located at x=-a and x=a are both fixed at their locations. Is the positive charge located at x=0 in equilibrium? If so, is it stable or unstable equilibrium?
b) What would be your answer if the situation was as shown below?
c) Find the frequency of small oscillations about the equilibrium points for above cases? Assume all charges have the same mass, m.