| MadSci Network: Physics |
Spike
500 Watts of electricity is a measure of how much power there is. What does the damage is the electrical current and whether it is an alternating current or direct current. The power and current are related by the equation power=current squared times resistance, or P=I**2 R. The resistance of your skin is quite high, several mega-ohms per metre, so you should not conduct a large current.
If this was 500W of direct current then you should only suffer a very bad shock and superficial skin burns. If it was alternating then you are in trouble. It only takes 4-5 milli Amps at 50 Hertz to cause your heart to go into shock, called fibrulation, and then stop. At very high frequencies the current takes a direct route over your skin causing major burns and muscle contractions.
I will leave it as exercise to yourself to measure your skins resistance and work out if 500W of power equates to enough current to kill you. A hint,
current=sqaure root of (power divided by resistance) or,
___
I= \/P/R
put in some test numbers for resistance =1 M ohm
___________ ______
I = \/500/1000000 = \/0.0005 ~ 22 Milli Amps.
Even if your skin has a resistance of 10 M ohms, the current is 2 milli-Amps.
not enough to kill you maybe, but enough to put you in Hospital. Commercial power
lines often run at the Kilo or Mega Watt range, do not touch.