Warp <war### [at] tagpovrayorg> wrote:
> gregjohn <pte### [at] yahoocom> wrote:
> > He couldn't describe it to me in a way that didn't
> > seem to be a gross violation of physics.
>
>   Somehow that seems to be pretty common with certain subject matters.
>

OK, I'll try my best ;o)

>   For example, ask anybody, an expert or layman, why you can die from
> touching an electrical wall socket (which has at most 230 volts), but
> usually not from an electric cattle fence (which has tens of kilovolts)
> and you won't get a straight, rational answer. I have yet to get a
> proper answer from anybody (which wouldn't seem to violate the basic
> "U=RI" formula).
>
The cattle fence works with a defined charge at a high voltage, which will
result in a
quick pulse (only a few milliseconds) with very low overall energy. This doesn't
screw up your nerve system too much.
Mains current (230Vac) will keep your nerve system jammed long enough (your time
of contact will usually be much longer than a few milliseconds) so your heart
stops beating.


>
>   Or ask any physicist about the candle-in-a-glass experiment: You have
> a plate with some water, and a candle in the middle. Light the candle,
> put a drinking glass upside down on the plate so that the candle is inside.
> When the candle goes out, the water will be sucked inside the glass. Why?
> You will get approximately as many different answers as people you ask,
> none of which will be correct.
>
> --
>                                                           - Warp

When you put the glass over the candle, the air inside the glass will be warmer
than the environment. When the candle has used up all the oxygen, the air will
cool down and the inside pressure sinks, sucking in the water from the outside.

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