Capacitance
Capacitance: Whimhurst Machine
A Wimshurst machine is used to demonstrate the concept of capacitance and charge storage.
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- Wimshurst machine
A Whimshurst machine is used to demonstrate that for a fixed voltage, a greater charge is associated with a greater capacitance. This is done by observing the rate of the discharge between the electrodes and also the energy of discharge for each spark while the charging rate is maintained approximately constant.
Parallel Plate Capacitors
The dependence of the capacitance on different variables is demonstrated.
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- Various capacitors
- Parallel plate capacitor with adjustable gap
- A piece of dielectic (glass)
- Capacitor with variable effective area
- Capacitance meter
- Connecting wires
Capacitors of various sizes, shapes, and capacitance values are shown. It is demonstrated, that for a parallel plate capacitor, the capacitance varies directly with the dielectric constant and area of the plates and inversely with the separation distance.
Charge and Discharge
A capacitor is charged and then slowly discharged through a light bulb.
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- Battery
- Capacitor
- Light bulb
- Knife switch
- Connecting wires
A large capacitor is first charged using a 12 V battery. It is then disconnected from the battery and discharged through a light bulb. The discharge time is observed as the light bulb slowly dims.