PURPOSE: To demonstrate electric charge.
DESCRIPTION: Strike the paper towel with the acrylic rod (as if you were striking a match) to get a positive charge on the rod. Place the charged rod onto the electroscope to show that the leaves deflect. Strike another paper towel with the PVC rod to obtain a negative charge. Place the charged rod onto the electroscope to show that the leaves deflect.
The charged rods can be used with the foil leaf electroscope and projector, as shown above. Or they can be used with the rotating pivots, demo number 5A20.10.
Here are some web references:
Bill Beaty http://www.amasci.com/emotor/tribo.html
Ron Kurtus http://www.school-for-champions.com/science/static_materials.htm
Thomas B. Jones http://www.ece.rochester.edu/~jones/demos/triboseries.html
EQUIPMENT: Acrylic rod, PVC rod, paper towels marked "+" and "-", foil electroscope with verticle overhead projector.
SETUP NOTES: The rods are stored in the Electricity and Magnetism cabinets in the drawer marked "Static Electricity". Paper towels are in the dispenser by the sink. Mark each towel "+" and "-". The foil electrometer is stored in the Electricity and Magnetism cabinet. The verticle overhead is stored in the vault.
REFERENCES: Duane Roller and Duane H. D. Roller, The Prenatal History of Electrical Science, AJP 21, 343-356 (1953).
Robert C. Plumb, Triboelectricity, Journ. Chem. Ed. 48, 524, (1971)
D. S. Ainslie, What are the Essential conditions for Electrification by Rubbing?, AJP 35, 535-537, (1967).
Stanley Anderson, An Experiment to Demonstrate that "Friction" Electricity Depends on Contact Potential, AJP 144, (1936).
Gilbert O. Spencer, Demonstrations in Electrostatics, AJP 26, 269, (1958).
Catalog Description, The Equipoise Electroscope, CCM School Materials Inc.
Randal Harrington, Getting a charge out of transparent tape, TPT 38, 23-25 (2000).
Updated by RR on 6/20/2007