Corona Discharge

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 Code Number :   5B30.35

Disclaimer:

Reprinted by permission of Dick Berg, University of Maryland, for use on this website.

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Condition :   Excellent  
Principle :   Corona Discharge, Surface Charge Density  
Area of Study :  Electricity and Magnetism   
Equipment :   Van de Graaff Generator, Ball with Retractable Metal Spike.  

Procedure :   Set the apparatus as shown. Retract the metal spike and start the generator. Notice that there is charge buildup but no arcing between the spheres. Stick the spike out of the ball and point towards the generator and note the arcing. Turn the spike away from the generator and observe the corona. This is best observed in a darkened room. Refer to Eb - 2 for charge sign information. In our case the Van de Graaff generator should have a negative charge.  

A much easier way to demonstrate corona is to put the pinwheel onto the point of either of the two larger Tesla coils.  Very nice corona will be visible at each point of the pinwheel.

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   References

Lester Dwyer, Lee Ihlenfeldt, Captain Bobby N. Turman, "Is a Swimmer Safe in a Lightning Storm?", TPT, Vol. 18, # 5, May 1980, p. 388.

Richard E. Orville, "The  Lightning Discharge", TPT, Vol. 14, # 1, January 1976, p. 7.

 

J. B. A. Mitchell et al., "Nanoparticles in Ball Lightning", Physics Today, Vol. 61, # 2, Feb. 2008, p. 18.

E. Philip Krider, "Benjamin Franklin and Lightning Rods", Physics Today, Jan. 2006, p. 42.

 

Eb-2: Freier and Anderson,  A Demonstration Handbook for Physics.

 



Mail Questions and Comments to:  Dale Stille