A conducting rod PQ of mass m and length l is placed on two long parallel (smooth and conducting) rails connected to a capacitor as shown. The rod PQ is connected to a non conducting spring of spring constant k, which is initially in relaxed state. The entire arrangement is placed in a magnetic field perpendicular to the plane of figure. Neglect the resistance of the rails and rod. Now, the rod is imparted a velocity v₀ towards right, then acceleration of the rod as a function of its displacement x is given by