Date: Tue, 12 Feb 2002 10:15:14 -0500 (EST)

Author: Richard Berg

Subject: Re: VDG/Tesla coil


On Tue, 12 Feb 2002, Jerry Hester wrote:

> Richard Berg wrote:
> > Snip.... We do an experiment
> > where we light a fluorescent tube by holding one end near the secondary of
> > the final coil, and that current must go somewhere (into the holder?).
> >
> This doesn't sound quite right. The current doesn't have to go anywhere, in fact
> you don't have to hold the bulb. You can lay it on an insulator. With a rapidly
> changing ac field, the electrons are busily running back and forth from one end of
> the bulb to the other without ever making any progress. They do however suffer
> many collisions in the process. If you create an arc (spark), then you definitely
> have current going somewhere.

Yes, by definition the current has to go somewhere. If there were no
place for it to go, it would not go, I think, and the bulb would not light
up. If the other end had infinite impedance no current would flow,
would it? If you don't hold it, the current probably goes out the
opposite electrode of the tube. If you hold it, I presume that at least
some of it goes through you. The last time I did it (as far as I
remember) the bulb got brighter when you held it. It certainly doesn't
kill you.

Dick Berg

> --
> Jerry Hester
> Laboratory/Lecture Demonstrations Coordinator
> Department of Physics
> Michigan Technological University
> 1400 Townsend Drive
> Houghton, MI 49931-1295
> Phone: (906) 487-2273
> Fax: (906) 487-2933

Dr. Richard E. Berg, Director Phone: (301) 405-5994
Lecture-Demonstration Facility FAX: (301) 314-9525
Department of Physics e-mail
University of Maryland
College Park, MD 20742-4111
If you think education is expensive, try ignorance.
Derek Bok,
Former President, Harvard University