On Sun, Jul 5, 2009 at 10:00 AM, Gerhard
Fiedler<lists@connectionbrazil.com> wrote:
> solarwind wrote:
>
>> People say current kills. So what happens if you push 1 mA through an
>> LED @ 1000 V? Will the LED blow?
>
> I don't know who said that in what context, but if it's about people
> being killed, it has not much to do with LEDs. Both scenarios have to do
> with the fact that voltage and current are tied together by the
> impedance of the device you're looking at. (It's called "Ohm's Law",
> which I think is kind of a misnomer. It's not a law; there aren't any
> laws in science (which is a good thing -- there are no lawyers either
> :). It's more something like "Ohm's Definition", as it defines the
> relationship between voltage, current and impedance.)
>
> As far as LEDs go, if you put 1000V directly across a LED, there will
> flow much more current than 1mA (for a short time). If you push 1mA
> through it, there will be much less voltage across the LED than 1000V.
> Can't have it both; they are tied together by the LED's impedance.
>
> As far as people go, their impedance varies wildly, especially the
> contact and ground resistances. Given that you are touching some source,
> one thing that is important for the danger you're exposed to is the
> current that is flowing through you. (Another thing is where the current
> is flowing through.) If you're well isolated from ground, you can touch
> a higher voltage source, because the higher ground resistance reduces
> the current that is flowing. But, of course, in the end it also comes
> down to current and voltage being tied together by the impedance. As
> approximation, talking about the "current that kills" makes sense in
> certain contexts.
>
> <http://hyperphysics.phy-astr.gsu.edu/hbase/electric/shock.html>
>
> Gerhard

So what happens if you have a 1000 V potential across the LED, but
some sort of limiter that only allows a max of 1 mA to flow?

And why is it that if you touch a 120 V source, you die - yet a 15000
V static shock merely stings?
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