Re: Magnetic Force with Tesla Coil?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Bob \(R.A.\) Jones" <a1accounting-at-bellsouth-dot-net> 

Hi
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, July 09, 2004 4:03 PM
Subject: Re: Magnetic Force with Tesla Coil?


 > Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net>
 >
 >
 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Friday, July 09, 2004 6:35 AM
 > Subject: Re: Magnetic Force with Tesla Coil?
 >
 >
 >  > Original poster: "Bob \(R.A.\) Jones" <a1accounting-at-bellsouth-dot-net>
 >  >
 >  > Hi,
 >  >
 >  > Actually the magnetic field will only penetrate to a skin depth(1/e) of
 > the
 >  > material at the relevant frequency.

Perhaps you did not notice the (1/e) in my reply.

In any case I agree.
 >
 > This isn't precisely true.  The skin depth represents a depth where IF the
 > current distribution were uniform, would have the same total current as
the
 > real thing. That is, the total current is equal to d * current density.
In
 > reality, the current (or field) tapers off as exp(-d/skindepth).  At the
 > "skin depth" the magnitude of the current (not the phase!) is exp(-1)
(about
 > 37%), but the current still extends deeper (theoretically to infinity). so
 > the total current is integral(0to infinity) [d * J(d)]dt (Where J(d) is
the
 > current density). Since, in uniform materials J(d) = exp(-kd), you can
make
 > use of the fact that integral(0to1) exp(-x)dx = 1.
 >
 >