Re: Watts or Amperes

[roger haar <haar@soliton.physics.arizona.edu>]

Hi,

	I am a bit confused about your understanding of 
electricity.  First, I have touched both terminal of a car battery
many times and have never even noticed it much less been killed.

	The question of if it is volts or amps seems to imply that they 
are independent rather than related by the resistance I R = V.


	There are two main ways that electrical shock can kill.

	The first and most common is a shock through the heart the
interfers with the normal electrical signals in the heart.  Usually 
those who have had their hears stop by shock can be saved by CPR.
Interesting, ( I got this from an engineer involved in hospital
safety) the US chose the worst line voltage (110 V) and the worst 
line frequency ( 60 Hz) possible.  The European 220 V 50 HZ, is actually 
safer because the shocks do not ususally have the same size as normal
heart signal.

	The second way that electrical shocks can kill requires much 
higher voltages ( several thousand volts at least).  These cause celluar
damage, and in the worst case the body fluid boil, and the steam flash
cause the body to explode.  Note many laboratory high voltage power 
supply are relatively safe because the may produce 10,000 volts if there is
only a small ( 0.0001 A) current drain, the output voltage drops quickly 
if more current is drawn.  Thus the voltage applied to the body for any 
length of time is much less than the peak voltage.  A van de Graaff
produces something like 100,000 volts but this drops to a almost nothing if 
you put your hand on it.



**************************************************************** 

On Fri, 8 Nov 1996 msantos@etse.urv.es wrote:

> Hi al,
> I thing there was a discussion some time ago
> on that topic but I cannot find any file refering
> to this:
>
> Why does it kills you when touching for instance
> the electrode of a car battery? (12V & 30-400A)
> Is it the high current the can supply or the
> power? may be both thing depending on the quantity
> of watts or amperes the can supply us when we touch
> the battery?
>
> My believe was that our body-cells get burned hence
> power was responsible.
>
> Regards
> msantos@etse.urv.es