Re: E field Angle

Dear Bill

Figure out your source conditions, solve the boundary value problem,
with Smyth's book on EM a very good reference for this problem. If
it is an induction source then the paper "Analytical Solutions to
Eddy-Current Probe-Coil Problems" Journal of Applied Physics Vol 39
p2829 (1968). Works for conductors only, not real ferromagnets.

J. Wallace

Bill Miller wrote:
Hello DN and thanks for the reply...

Actually I am interested in AC/RF performance when a current is flowing
through the conductor. (I'm sorry I did not mention that!)

. I'm familiar with skin depth data and formulae, but the information
doesn't seem to be applicable to the E field angle (or I do not understand
how to interpret it in that way!)

The interface I am interested in is very simple -- metal -to - air (or
vacuum).

Bill Miller


"Douglas Natelson" <natelson@xxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:e95jfd$eah$1@xxxxxxxxxxxxxxx
Bill Miller wrote:
Theoretically, the Electrical (E) field associated with a conductor is at
exactly 90 degrees with respect to that conductor.

That's true for dc fields. The surface of the conductor is all at the
same potential (if it wasn't, current would start to flow to screen
out the potential differences). Since the E field is proportional
to the gradient of the potential, it has to be normal to the conducting
surface.

It appears, however, that real conductors behave diffeeently and that the
E field associated with a real conductor is at an angle that is slightly
displaced from 90 degrees.

Only at nonzero frequencies.

What are the parameters that govern this angle, and what is the range of
angles that is likely to be encountered with typical conductors such as
Cu, Al, Ag and others?What angular difference (if any) is there between a
DC field and an AC field with the same peak V/M amplitude?

The complex dielectric function as a function of frequency is really
what determines the boundary conditions. For truly dc fields,
the field is locally normal to the surface. Try reading up on
"skin depth" and related terms.

--DN


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