Subject:  Re Faraday's cage
Date:     Wed, 9 Jul 1997 054449 -0500 (CDT)
From:     Clas Tegenfeldt <tegen@bemi.se>
To:       Multiple recipients of list <emf-l@mail.llion.org>
--------------------------------------------------

At 05:57 1997-06-27 -0500, you wrote:
>Hi everybody,
>A Farady cage is a room totally encapsulated in metal or metal net which
>is grounded, which shall make it impossible for electric fields to
>enter. It's however extremly difficult to make one that's works 100%. It

For the Faradys cage to work properly is does NOT, repeat not, need to be
"grounded". Ground, earth or soil has nothing to do with Faradys cage.

What the cage does is to equalize the potential differences at all points at
the surface (boundary) of a contained space. Inside that space there is no
potential differences and thus no electric field.

Magnetic (near) fields are another matter altogether, please remember that
Faradys cage only protects against electric fields and electromagnetic (far)
fields to the extent given by material properties and size of the
discontinuities
(holes) in the electrically conducting surface.

So, a Faradys cage does not need to be earthed at all to work.

Clas Tegenfeldt       ,,,
                     (o o)
------------oOOO------(_)------OOOo-------------------
      BEMI - Better Electromagnetic Enviroment
BEMI                     Telephone/fax +46 (0)13-74075
Tornevalla Gamla Skola   Timezone      GMT-1
S-590 62 LINGHEM         E-mail        tegen@bemi.se
SWEDEN                   Web           http://www.bemi.se


Archive provided courtesy of WaveGuide, http://www.wave-guide.org
Reprinted with permission of Roy Beavers, http://www.feb.se/EMF-L/EMF-L.html