College of Liberal Arts & Sciences
5H30.35 - Rotating Plasma - DC Arc
Code Number:
References:
5H30.35
Demo Title:
Rotating Plasma - DC Arc
Condition:
Good
Principle:
Magnetic Fields and Plasmas
Area of Study:
Lorentz Force
Equipment:
Induction Coil, Round Electrodes, Magnet in Stand, 12 Volt Power supply.
Procedure:
Video Credti: Jonathan M. Sullivan-Wood.
Place the electrodes directly on top of the magnet stand so that centering them is easier. Clean the electrodes with the 3M cloth before use.
12 volt DC input on the induction coil. Watch how close the wires are on the high voltage DC output sides. Also, don’t touch the high voltage wires when the unit is operating.
Alignment of the outer points bar on the induction coil is critical for the operation of this demo. It may need to be moved up or down slightly for it to operate acceptably.
You may need to flip the reed flapper on the induction coil unit to get it started after you turn on the 12 volt input power supply.
The demo should make a high pitched whine like a nest of angry bees when operating as it should.
The 12 volt input should run at 1 amp or less when it operation. If it is drawing too many amps, the points alignment is not right and the unit is in danger of burning out.
As shown in the movie, the spark (with its plasma sheath) will reverse rotation direction if you switch the wires on the high voltage DC output terminals. You could also do this by flipping the magnet over, but in our case, that is tied down so the magnet can’t “get away” from you.
- James Lincoln, Nick Moore, "Five Fresh Lorentz Force Demos", TPT, Vol. 57, #8, Nov. 2019, p. 572.
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.