Jacob's Ladder

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 Code Number :   5D40.10 

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.

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Condition :   Excellent  
Principle :   High Voltage Arcs 
Area of Study :  Electricity and Magnetism   
Equipment :   Large Oil Filled Transformer inside metal box with handles, Long Antenna mounted on Plexiglas holder, Insulated Connecting Wires, Induction Coil, Antenna for mounting on Induction Coil, Plexiglas Tube Cover.

Procedure :   Attach the antenna app. to the transformer using the insulated wires designed for this purpose. Position the gap so that the spark starts at the bottom of the antenna when the transformer is turned on. The spark should travel upward the length of the antenna if they are set correctly. Always turn off and unplug the transformer when working on it as it is putting out lethal voltages. The large plastic pipe may be placed over the antenna to keep air currents in the room from affecting the travel of the spark. 

The transformer may be replaced with the induction coil. Although it is not as powerful you can still get the spark to travel 3/4 of the way up the antenna if it is adjusted properly. There is also a smaller set of antenna that may be used with the induction coil if you do not want to use the large set. A Plexiglas tube cover will help this demo immensely.  

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   References

Em - 3:  Freier and Anderson,  A Demonstration Handbook for Physics.

 

6.3:  Jearl Walker, "Getting Stuck to Electric Wire," The Flying Circus of Physics with Answers.

Atomic and Electronic Physics, p. 436.

Ron Hipschman, "Jacob's Ladder," Exploratorium Cookbook II, p. 93.1 - 93.2.



Mail Questions and Comments to:  Dale Stille