PASCO Basic Electrostatics System - Page 23

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ES-9080A 012-07227G Basic Electrostatics System
23
voltage source. Take care to place the capacitor sufficiently far away from the sphere and the
voltage source, to prevent it from being charged by induction.
2. Press the ZERO button to remove any residual charge from the electrometer and the
plates of the capacitor.
3. Set the plate separation to about 2 mm. Use a proof plane to transfer charge from the
charged sphere to the capacitor plates. The charge is transferred merely by touching the
proof plane to the sphere and then to one capacitor plate. If you always touch the sphere
and the capacitor plate at the same place, equal amounts of charge will be transferred each
time.
Question: Why is it sufficient to touch only one plate of the capacitor?
4. Observe how the potential difference reading from the electrometer varies as more charge
is put in the capacitor.
Figure 3.2: Demonstration Setup
Electrometer
Electrostatics
Voltage
Source
To AC power
adapter