Natural Science Forum / Physics / Electromagnetism / April 2007

I'm just a layperson fascinated by electromagnetics.
I understand that we can often conveniently imagine electrons to be charged
solid particles. When an object has an excess of electrons that object is
negatively charged and will give rise to an electric field around it. If

Zenneck waves are, apparently, EM waves that exist at the boundary of two
dis-similar dielectric materials. Air and ground would be one such
interface. An unusual aspect of this mode is that -- apparently -- the
radiated wave decays as 1/SQRT(r) rather than 1/r.

It's been so long since I dealt with e-mag stuff in college, I was
hoping some folks here to help answer my questions or point me to some
good refresher materials, or both..
I'm looking to rotate a magnet within a coil of wire to induce

The intrinsic space impedance is 377 (120*pi) Ohms.
The impedance of a dipole antenna is 73 Ohms.
Whst is the relationship between these two impedance values?  Should
the antenna have mached impedance as that of the EM wave in space?

How do you call a "solenoid with a non moving nucleus" (like a
holding electromagnet but with a single pole at one end) ?
I just need to repulse a fixed magnet.
Do you know of any manufacturers of such devices ?

Here's another simple question.
We all know that self-inductance is basically determined only by the
geometry of conductors in space.  [Except for a few material
properties etc.]

I have a cable and I send electric current through it. I want to know
the moment when the current has arrived at the other end of the cable.
Can I visualize this moment by using an oscilloscope ?
If the answer is yes, I have another question for a more complex

Hello Light Speed Investigators,
It appears that in building the Light Speed versus Special Relativity
article for the web, too many bells and whistles were added that clouded the
main argument.

Hi, everyone.
I want to get a data of metal epsilon such Ag, Au and so on. I thing
if the temperature
of metal changes epsilon have to change. Doesn't it?

I've grown very intrigued lately with the "polywell" approach to fusion,
developed by Robert Bussard.  A brief description is given here:
 <http://en.wikipedia.org/wiki/Polywell>
In the WB-6 machine shown at the top of that page, all the magnetic