Question

A thin disk with a circular hole at its center, called an annulus, has inner radius R1and outer radius R2. The disk has a uniform positive surface charge density (sigma) on its surface. A point particle with mass m and negative charge -q is free to move along the x-axis (but cannot move off the axis). The particle is originally placed at rest at 0.01R1 and released. Find the frequency of oscillation of the particle. Express your answer in terms of the variables R1, R2, (sigma), m, q, and appropriate constants.