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Concepts

Coulomb repulsion, grounding

Overview

The Project-o-scope can be charged by induction by bringing a charged rod close to it and touching the metal disc with a finger. The Project-o-scope will deflect its needle in response.

Details

Equipment

• [1] Project-o-scope
• [1] Cellophane
• [1] Glass rod
• [1] Rabbit fur
• [1] PVC rod
• [1] Box of matches
• [1] Lighter

Important Notes

• As with most electrostatic demonstrations, this works best on cool, dry days.
• Fur on PVC gives the rod a positive charge.
• Cellophane on glass gives the rod a negative charge.

Script

1. Rub the fur on the PVC rod.
2. Bring the PVC rod close to the metal disc.
3. Tap the Project-o-scope plate with your finger. The Project-o-scope needle should deflect.
4. Rub the cellophane on the glass rod.
5. Bring the glass rod close to the metal disc. The needle should go back towards 0.
6. Light a match or ignite the lighter near the plate of the Project-o-scope to discharge it.

Additional Resources