>In a message dated 97-12-10 14:14:07 EST, you write:
>
><< >With a sensitive instrumentation amp you can measure the voltage
> difference >between your feet and your head (usually a couple hundred volts
> over six feet).
>
> This is really interesting!
>
> But if it's a couple of hundred volts, why do you need a sensitive
> instrument amp?
>
> Bruce
>  >>
>Also, if this is true (now that we are thinking about it) why do we not notice
>it in this case, but if we put a 115V mains on our head and stood on a copper
>pipe to earth we would be paramedic material??
>

Because there is almost no energy stored in the charge. Air--unionized, at
least--is an excellent insulator, but a pretty lousy capacitor for energy
storage (near infinite ESR!).

--BN


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