Demonstrations

Household Electronics

Code Number :	5F15.15
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 :	Household Electrical Measurement and Protectors
Area of Study :	Electricity & Magnetism
Equipment :	Mounted and Unmounted Watt Meters, "Watts Up?" watt meter, Power Strip with 2 amp Circuit Breaker, Break apart Circuit Breaker, 1000 Watt Light Bulb, Variac, Drill.
Procedure :	Plug in the mounted watt meter unit. Plug the 1000 watt light bulb directly into the Variac and the Variac into the mounted watt meter socket. Now as the Variac is turned up the meter functions may be observed. Note that there is some current flow even when the Variac is turned to the zero position. This is a normal Variac characteristic. Plug the power strip into the watt meter unit. Plug the Variac into the power strip and the 1000 watt light bulb into the Variac. Turn up the Variac and observe that when the power usage reaches about 1 1/2 times the circuit breaker value the breaker will trip. The watts up meter may be used in place of the wooden mounted watt meter with some precautions. The big drawback is that this meter must have 120 volt input or the LCD functions do not operate.

References

William P. O'Brien Jr., "Hassle-Free Energy Consumption Measurements of Electrical Devices", TPT, Vol. 46, # 5, May 2008, p. 310.

Steve Dial, "Safer Plugs for Measuring Wattage", TPT, Vol. 45, # 8, Nov. 2007, p. 468.

Dick Heckathorn, "No-Shock Alternative", TPT, Vol. 45, # 6, Sept. 2007, p. 326.

John J. Lynch, "Wattage: Household Appliances," TPT, Vol. 45, # 4, April 2007, p. 249.

Robert Johns, "Simplifying AC-Current Measurements", TPT, Vol. 39, # 5, May 2001, p. 314.

Sarah Fay and Angela Portenga, "Hey You! Shut the Refrigerator Door!", TPT, Vol. 36, # 6, Sep. 1998, p. 336.

Lawrence Ruby and John Hunt, "Understanding Modern Electrical Protective Devices," TPT, Vol. 35, # 7, p. 432 - 434, (Oct. 1997).

"Figuring Physics", TPT, Vol. 28, # 2, Feb. 1990, p. 113.

H. Richard Crane, "On Electric Shocks and Spinning Eggs," TPT, Vol. 27, # 4, p. 300, (April 1989).

H. Richard Crane, "A New Department", TPT, Vol. 21, # 4, Apr. 1983, p. 254.

Courtney Lantz, Charles H. Anderson, "Why Is The Ac Power Line Grounded?", TPT, Vol. 18, # 4, Apr. 1980, p. 314.

Harry H. Kemp, "Lenz's Law", TPT, Vol. 15, # 9, Dec. 1977, p. 543.

Ron Hipschman, "Watt's the Difference," Exploratorium Cookbook III, 156.1 - 156.3.

Mail Questions and Comments to: Dale Stille