- Large Parallel plate capacitor
- Rods and fur
- Large Kilovolt potentiometer
- Two short wires
- Connect both wires from the capacitor to the kilovolt meter (grounded wire on insulated plate). The wires should not be touching anything, so use short wires (else a charge won’t stay on the plates).
- Test to make sure the plates hold a charge.
- Start with a large air gap.
- Use the fur to charge up the rod. Put the charge on the insulated plate.
- Move the plate closer and note that the voltage of the capacitor changes.
- To discharge the plates, touch your hand across both.
Note: Works best with less then 50% humidity.
Concept: The idea here is to show that the potential difference in a parallel plate capacitor is linearly proportional to the distance between the plates (V=dQ/εA). The potential should rise as the plates are separated further, and should decrease as they are pushed closer together.