Mounir,
Doen't stun guns produce about 5000 volt? That at least doesn't
kill a person.
Voltage doesn't kill or even hurt anyone. I once had an electronics teacher
in high school who said he had to wet his fingers to feel the 120 V power
line. Of course he was kidding, but he was old and his skin was dry and his
resistance was high. What 'hurts' is power, and probably energy. Power is
voltage times current. The high voltage section of a TV set delivers about
30,000 volts, but the power supplies in those set are not designed to deliver
enough current to kill someone. I suppose it's not impossible but would
depend on the health of the person, etc. Those power supplies are also
designed to shut down when the load draws more current than it's supposed to,
i.e. when a person is getting zapped. Of course one would still feel that
power briefly. I used to tell me students that if they touch the high voltage
lead on a TV set they would probably cut themselves. That's because there are
some sharp corners inside the set we were working on. Here's the math:
The average person has several thousand ohms of resistance between those
critical two points on the body, the hands. (It's critical because death
results from current to the heart, usually AC). If the shocking voltage is
the 120 V. power line one could draw 120 milliamperes or more in that case.
It takes about 1 mA for you to feel it and more to kill you. I have a chart
that gives the correct figures. We took a student and increase the voltage we
had applied to him while measuring the current and when he yelled we figured
he had felt it. When he died we knew what amount of current it took to kill
him... Gotcha!!!
So it takes power, and probably energy, i.e. power times time to do work and
certainly to kill someone. Those defibrillators you see on the medical shows
operate in the thousands of volts, but their force is measured in Joules,
i.e. Watt Seconds.
Jim
