Natural Science Forum / Physics / Electromagnetism / July 2005

BETH - A Trilogy
How does one civilization convey its
collective wisdom, knowledge, and memories
to another, perhaps alien, civilization?

<<Figure 12.4: A plausible guess for how the fields lines between the two views shown in figure 12.2 must connect. The second
picture shows the view a little further out and the third picture shows the pattern far away from the oscillating current source.
The last picture shows an ...

My understanding of Maxwell's equations leads me to believe that, in a
propagating wave, the magnetic field strength is proportional to the time
derivative of the electric field, and vice versa.  This would seem to imply
that, at an instant in time, the magnetic field is zero at ...

I arrive at this question in a strange way. Strange and pretty. Our
best estimate of the total mass of the observable Universe is 10^30 kg
for our Sun times the average number of stars per galaxy is 10^11 times
the total number of galaxies is 10^10 which gives us the total mass of

Is angular momentum not conserved when an atom emits an individual
photon?
Consider an atom that makes a transition from an initial state with
quantum numbers j = 1, m = 1 to a final state with quantum numbers j =

I have an electrostatic problem.  I have never studied EM aside from
minimal exposure to the topic while completing a degree in mathematics 30
years ago.
We have a rectangular test cell, dimensions w by h containing a uniform

Man, you won't regret watching this show, it's incredible!!
Tune In:
Saturday, July 9, 2005 @ 11am ET/PT
The remarkable story of the men who maintain and repair live

I am using an IMU made of MEMS that has the particularity to provide
not only acceleration, rate of rotation but also heading.
The heading is a mangetic one. When I use this unit in my car, I have
noise in readings at two levels. First, it looks like I have DC

Wire mesh or parallel bars are often used as a replacement for solid
reflectors (for example to reduce wind load).
Is there any practical formula, computer program or graph for
calculating the (plane wave) reflectivity/reflection coefficient of

I am interested in the heating effects on rotating shafts in magnetic
fields.
If a hollow shaft is rotating at high revs inside a collar of static magnets
will a  heating effect occur on the surfaces of the shaft? How can it be

The Pentagon has admitted that the U.S. intelligence agencies called the
N.S.A. [ National Security Agency ], C.S.S [ Central Security Service ],
D.I.A. [ Defense Intelligence Agency ], D.A.R.P.A. [ Defense Advanced
Research Projects Agency ], C.I.A. [ Central Intelligence Agency ], ...

I'd like to ask 3 questions:
1. Is this the main NEC users forum ? I recently tried the NEC mailing
list but is didn't seem to be operational.
2. Which modelling programs are considered state of the art in terms of

  I don't understand magnetism at all, but it is fun to think about.
  When you push poles together, and they repel, it feels just like water
pushing back.
  When I put an empty glass into a bown of water all the way to the bottom,

Hi group readers,
I realize the conductivity of steel is some 30-40 times worse than that
of copper.  But for RF (10-100MHz) applications, it is the skin effect
that matters, then the surface conductivity of stainless is "only" six