Mystery Top


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 Code Number :   5K40.49a  

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:  U of Iowa Dept. of Physics and Astronomy Disclaimer.

Condition :   Excellent  
Principle :   Motors, Elec. & Mag.  
Area of Study :  Perpetual Motion  
Equipment :   Mystery Top Demo, Fresh 9 Volt Battery.  
Procedure :   The top demo is really a specially designed brushless DC electric motor. The small top corresponds to the rotor and flywheel of a motor. It actually has a small bar magnet in it. In the base are a battery, coil, steel core, and transistor. These create the magnetic field that power the small top. As the small top moves around on the surface of the base the motor is turned on and off by the top leaving and entering the small magnetic field which is concentrated at the center of the base. The transistor is nothing more than a sensing switch. The battery should last for 5 to 7 days continuous running. The top runs at approx. 2500 rpm and full battery strength.  
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 Web Links

"The Museum of Unworkable Devices." www.lhup.edu/~dsimanek/museum/unwork.htm

 

   References

Arthur Schmidt, Peter Insley, "Perpetual (?) Spinning", TPT, Vol. 22, # 9, Dec. 1984, p. 594.

H. Richard Crane, "A Spinning Top, Lenz's Law and Electric Watches", TPT, Vol. 22, # 2, Feb. 1984, p. 113.

C.L. Stong,  "An Electrometer, a Temperature Control Apparatus, and a Simple Electric Motor,"  The Amateur Scientist,  (October, 1965).



Mail Questions and Comments to:  Dale Stille