A small plastic ball of mass $8\mathrm{.}76{10}^{-3}kg$ and charge $+0\mathrm{.}135C$ is suspended from an insulating thread and hangs between the plates of a capacitor $($see the drawing$).$ The ball is in equilibrium, with the thread making an angle of $30\mathrm{.}0$ with respect to the vertical. The area of each plate is $0\mathrm{.}02095m^2.$ What is the magnitude of the charge on each plate?

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