Coulomb's Law Balance - Pasco Model



5a20.37b.jpg (41248 bytes)5a20.37c.jpg (107037 bytes)5a20.37d.jpg (100748 bytes)

 

 

content.gif (1503 bytes)
 Code Number :   5A20.37

Disclaimer:

Disclaimer

These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.

Condition :   Good  
Principle :   Electrostatics, Coulomb's Law
Area of Study :  Electricity & Magnetism   
Equipment :   6 KV power supply, Coulomb's Law balance (Pasco Model), charging paddles, high voltage charging probe.

Procedure :   Zero the torsion pendulum before putting charge on the balls.  Set the power supply at 5000 volts and touch one or both of the balls.  Electrostatic repulsion or attraction can be shown and measured with this device.

An interesting variation is to use only the torsion balance part of the apparatus and a metal plate.  When the ball is charged, a "mirror charge" will be induced on the plate.  The ball on the torsion balance will swing over, touch the plate, then be repelled.  

A discrepant event of the above demo is to use the black painted plate instead of the bare metal plate.  In this case the ball will stick to the metal plate. 

conbot.gif (53 bytes)
   Websites
Electric Field Applet 

http://www.cco.caltech.edu/~phys1/java/phys1/EField/EField.html 


   References
Peter Bohacek, Matthew Vonk, Joseph Dill and Emma Boehm, "Letting students discover the power, and the limits, of simple models: Coulombs law", TPT, Vol. 55, Septermber 2017, P. 380.

Subbho Banerjee, Kevin Andring, Desmond Campbell, John Janeski, Daniel Keedy, Sean Quinn, Brent Hoffmeister, "Orbital Motion of Electrically Charged Microgravity", TPT, Vol. 46, # 8, Nov. 2008, p. 460.

Peretz D. Partensky and Michael B. Partensky, "Hanging by a Thread", TPT, Vol. 44, # 2, Feb. 2006, p. 88.

Michael Partensky and Peretz D. Partensky, "Can a Spring Beat the Charges?", TPT, Vol. 42, # 8, Nov. 2004, p. 472.

Peter Anderson,  "A Wind Shield for the PASCO Coulomb Apparatus",  TPT, Vol. 41, # 1, p.  51, Jan. 2003.

C. H. Worner, "On the Teaching of the Electric Dipole", TPT, Vol. 39, # 8, Nov. 2001, p. 462.

Robert Weinstock, "Two-Charge Dipole Revisited", TPT, Vol. 39, # 4, Apr. 2001, p. 218.

Christopher Bracikowski,  "Graphical Analysis of Electric Fields of Dipoles and Bipoles",  TPT, Vol.  38, # 1, p. 20, Jan. 2000.

Leon M. Lederman,  "Correction",  TPT, Vol.  38, # 9, p. 519, Dec. 2000.

Robert Weinstock,  "Electric Field of a Two-Charge Dipole: A Graphical Approach Extended",  TPT, Vol.  38, # 7, p. 430, Oct. 2000.

Scott W. Bonham, John S. Risley, and Wolfgang Christian,  "Using Physlets to Teach Electrostatics",  TPT, Vol.  37, # 5, p. 276, May 1999.

Adolf Cortel,  "Demonstrations of Coulomb's Law with an Electronic Balance",  TPT, Vol.  37, # 7, p. 447, Oct. 1999.

Robert J. Beichner, "Visualizing Potential Surfaces With A Spreadsheet", TPT, Vol. 35 # 1, Feb. 1997, p. 95.

Sonya Cooper, Narasimha Prasad and Budh Ram, "Defining a Coulomb of Charge", TPT, Vol. 33, # 4, Apr. 1995, p. 198.

MArcelo Alonso, "More on the Coulomb", TPT, Vol. 33, # 6, Sept. 1995, p. 326.

Josip Slisko, Arkady Krokin, "Physics or Fantasy?", TPT, Vol. 33, # 4, Apr. 1995, p. 210.

David T. Kagan, "The Ultimate "Pith Balls", TPT, Vol. 29, # 4, Apr. 1991, p. 197.

Samaroo Deonarine, "Coulomb's Law After the Christmas Party", TPT, Vol. 28, # 9, Dec. 1990, p. 607.

Donald Mahoney, Clifford Swartz, "What is the Potential at a Point Due to a Line Source?", TPT, Vol. 22, # 6, Sept. 1984, p. 392 - 393.

Russell Patera, "Stability of the Coulomb Balance", TPT, Vol. 16, # 8, Nov. 1978, p. 565.

Wijit Senghaphan, Richard K. Fry, "Current Balance & Coulomb's Law apparatus", TPT, Vol. 12, # 7, Oct. 1974, p. 435.

D. F. Bartlett and E. A.  Phillips, "An Experimental Test of Coulomb's Law", TPT, Vol. 8, # 7, Oct. 1970, p. 403.

Francis W. Sears, " A Substitute for Pith Balls and Balloons in the Demonstration of Electrical Forces", TPT, Vol.1, # 5, Nov. 1963, p. 225.

 

Michael Levin, Steven G. Johnson, "Is the Electrostatic Force Between a Point Charge and a Neutral Metallic Object Always Attractive?", AJP, Vol. 79, # 8, August 2011, p. 843.

Bernard Roulet, Michel Saint Jean, "Image Charges Revisited: Beyond Classical Electrostatics", AJP, Vol. 68, # 4, p. 319, April 2000.

Ronald Shaw, "Symmetry, Uniqueness, and the Coulomb Law Force", AJP, 33, # 4, April 1965, p. 300.

P. H. Wiley and W. L. Stutzman, "A Simple Experiment to Demonstrate Coulomb's Law", AJP, Vol. 46, # 11, Nov. 1978, p. 1131.

 

 Lawrie Challis and Fred Sheard, "The Green of Green Function", Physics Today, December 2003, p. 42.

 

David Kutliroff, "81, Coulomb's Law on an Overhead Projectors", 101 Classroom Demonstrations and Experiment For Teaching Physics, p. 179.

W. Bolton, "Potential", Book 4 - Electricity, Physics Experiments and Projects, 1968, p. 24-25.

 



Mail questions or comments about this site to:  Dale Stille

The University of Iowa 2011. All rights reserved.