list:

kindly note that current and voltage are not independent, and that 100 mA
through the heart for 1 s would probably be fatal.

in the simplest cases, current and voltage are related fairly precisely
through ohm's law:

I = V/R

where I = current and V = potential difference across R. for example, if
12 volts is applied across a 300 ohm 1 W resistor, ohm's law implies that
a current of 12 V/300 Ohm = 0.04 A will flow through the resistor. it
makes no difference whether we say the voltage is 12 V on one side of the
resistor and 0 volts on the other, or 1,000,012 volts on one side and
1,000,000 volts on the other, we get the same 12 V potential difference
across the resistor, and the same amount of current, 0.04 A, will flow. in
this case, the power developed by the resistor would be 0.48 watts, within
its 1 W power rating. now, what if we substitute a 30 ohm 1 W resistor
instead? well ohms law would predict a 0.4 A curren and heat produced at
the rate of 4.8 W, nearly 5 times the power rating of the resistor; in
this case, ohm's law does its job in so far as letting us know that the
resitor would fry, but the resistor itself would change value
significantly as it burned up.

dlk

>The charge LED flashes fine even in pretty low light, but it's only
>indicating that there's voltage present... however there's nearly no
>current, and it's current, not voltage, which will charge a
>battery... or an electrocution! (a 100mA current of 1,000,000V will
>not even be felt).