[OT] Re: [Gllug] Electric Shocks

[Pete Ryland]

On Fri, May 16, 2003 at 12:31:09PM +0100, Tim Gray wrote:
> A) Yes.
> 
> As an aside, its also safe to sit/stand in a metal cage (faraday cage)
> when being shocked. The metal around you has a less resistance you are
> less like to get a jolt. If your ever caught out in a lighting storm get
> in a car.....

You're confusing two concepts here.  A faraday cage refers to faraday's
discovery that a sphere with a hole (or indeed many holes) in it has the
same electro-magnetic properties as a complete sphere.  Since
electromagnetic radiation (a radio signal for example) is disrupted by a
grounded sphere (the EM eddies generated in the surface produce a waveform
that cancels out the radio signal), then inside a grounded conductive cage,
you will not receive the signal, just as you wouldn't in a complete
conductive grounded sphere.  By extension, you can also prove that a cage of
any shape will act like a sphere.

This is different to high-voltage energy picking the path of least
resistence to ground - the fundamental concept behind the lightening rod,
and why you should lie down if caught in a flat field during a thunderstorm.
And why you shouldn't swim during a thunderstorm too.  A car, though, is
actually likely to be hit, but you won't be harmed since there's so much
metal to dissipate the energy.

Pete

-- 
pdr    - Pete Ryland              - http://pdr.cx/info/about/
xmldb  - FAST 3-tier app server   - http://pdr.cx/projects/xmldb/
GNetMD - suite of tools for NetMD - http://pdr.cx/projects/gnetmd/


-- 
Gllug mailing list  -  Gllug at linux.co.uk
http://list.ftech.net/mailman/listinfo/gllug