Demonstrations

Ohm's Law

Code Number :	5F10.10
Disclaimer:	Reprinted by permission of Dick Berg, University of Maryland, for use on this website. The demonstrations contained and referenced herein are listed for the purposes of cataloging and describing physics demonstrations which should be conducted only under the direction of a trained instructional support professional or physicist. These demonstrations are not presented for the purpose of being conducted by persons unconnected to this Facility and/or persons not consulting with or being supervised by the recognized instructional support professional or physicist and his/her staff. The University is responsible only for those demonstrations carried out using its own equipment using established safety and scheduling policies, and bears no responsibility for those choosing to use this source material for their own purposes. All demonstrations described and contained herein are public domain, and can also be found in reference materials in libraries, bookstores, and electronic sources. Further information regarding legal liability in use of demonstrations and labs will be found on the web site Injuries in School/College Laboratories in USA. The University of Iowa Disclaimers: University of Iowa Disclaimer All Rights Reserved..
Condition :	Good
Principle :	Series and Parallel Resistors
Area of Study :	Electricity & Magnetism
Equipment :	Dry cells (4) or 12 volt car battery, Resistors (assorted), Multimeter (2), Spare lamp bulbs, Calculator, Circuit board with Velcro fasteners, Lamp sockets with Velcro fasteners, Power Supply to use in place of the batteries if desired, Key Switches, Hot Plate Heating Element.
Procedure :	Hook the resistors or light bulbs into parallel and series pairs. Attach a Multimeter to each type circuit for measuring of voltages or resistances. Use an ammeter and a voltmeter when doing the Ohm's Law demos. Voltage dividers may also be constructed with this equipment. Ohm's law can also be demonstrated very well with the hot plate heating element. DC voltage is easier to work with when doing this demonstration so use a 0-20 volt or 0-150 volt power supply. Measuring the current, voltage and/or ohms and substituting into the V=IR equation gives you very accurate results. This example can be found in Physics by Cutnell and Johnson Fifth Edition on p. 593.

References

"Figuring Physics", TPT, Vol. 42, # 4, April 2004, p. 247.

Art Hovey, "Nomographs," TPT, Vol. 41, # 1, p. 4, (Jan 2003).

Thomas B. Greenslade Jr., "Additional Reference," TPT, Vol. 41, # 7, Oct. 2003, p. 380

Kavork Spartalian, "Rectangles in Physics," TPT, Vol. 41, # 7, Oct. 2003, p. 390

Pete Vreeland, "Analyzing Simple Circuits," TPT, Vol. 40, # 2, p. 99, (Feb. 2002).

Thomas B. Greenslade Jr., "A Nomograph for Resistors in Parallel," TPT, Vol. 40, # 8, p. 458, (Nov 2002).

Alison Hapka, "Magnetic Cards for Teaching Electronics", TPT, Vol. 37, # 3, Mar. 1999, p. 152.

Jack Higbie, "Proof of the R-2R Ladder Network", TPT, Vol. 35, # 8, Nov. 1997, p. 464.

Scott F. Rhodes, "A Working Model of Ohm's Law", TPT, Vol. 32, # 5, May 1994, p. 319.

Thomas A. Lehman, "Light on LED's", TPT, Vol. 31, # 5, May 1993, p. 262.

Steven A. Waltner and Thomas A. Lehman, "When Is Ohm's Law Valid?", TPT, Vol. 31, # 2, Feb. 1993, p. 102.

M. H. Ansarizadeh, E. F. Walker, "Solar Approach to Ohm's Law", TPT, Vol. 27, # 3, Mar. 1989, p. 217.

Bernard Scott, "An Intriguing Problem in Equivalent Resistance," TPT, Vol. 26, # 9, p. 578, (Dec. 1988).

Eo-1, 3, 5, 7: Freier and Anderson, A Demonstration Handbook for Physics.

E-380: "Simple Circuit," DICK and RAE Physics Demo Notebook.

Physics, Fifth Edition, Cutnell and Johnson, p. 593.

Ron Hipschman, "Ohm's Law," Exploratorium Cookbook III, p. 148.1 - 148.3.

"Ohm's Law in Simple Circuits", Selective Experiments in Physics, CENCO, 1958.

"Ohm's Law", Selective Experiments in Physics, CENCO, 1942.

Mail Questions and Comments to: Dale Stille