# Unchanged oscillations

Initially a system of two particles of masses connected by strings m=3kg charge q and M=8kg charge Q exist where m is on the frictionless table rotating with some angular velocity. The mass M is in equilibrium. Now we pull the mass M by some distance downwards. It oscillates with a certain frequency. We do the experiment again by placing a large disc of surface charge density $\sigma=7C/m^{2}$ so that its centre lies just below M. Surprisingly we find that the frequency of oscillations is unchanged. Find$\frac{q}{Q}$ assume that the charges are approximately at the same level (height) w.r.t the disc. also assume that the electrostatic forces are negligible between the two small charges throughout.

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