Figure shows a dumbbell consisting of two identical masses m? attached to the ends of a thin

Question:

Figure shows a dumbbell consisting of two identical masses m?attached to the ends of a thin (massless) rod of length a?that is pivoted at its center. The masses carry charges of +q?and ?q?and the system is located in a uniform electric field E. Show that for small values of the angle ??between the direction of the dipole and the electric field, the system displays simple harmonic motion, and obtain an expression for the period of that motion.