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Physics and Science Concepts
Charge the plates using the Van de Graaff. Disconnect wire going from top of sphere to fixed plate at plate end. Change the spacing of a charged parallel plate capacitor while it is attached to an electroscope. Observe changes in electroscope pointer.
Electroscope can be obtained from demo 5A22.22. The Van de Graaff can be obtained from demo 5A50.30.
Two parallel plate capacitors are charged and hooked up to an electroscope. When you change the distance between the plates, the electroscope pointer will move because the potential difference between the two plates changes.