The parallel-plate capacitor is connected to a high-voltage power supply with the electrometer connected in series to monitor the current (10 microamps). A ping-pong ball covered with conductive paint dangles between the two plates. When the power supply is turned on, the ball oscillates between the two plates, transferring charge. The higher the voltage or the closer the two plates, the higher the current (However, this is not a linear system).
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