help?

Thread Starter

liv

Joined Nov 7, 2004
6
:blink

Im doing an assessment for physics and i need some help in regards to electricity. I understand what happens en you get a shock and i know, obvioulsy, that its only when you get in contact with an electricity source. but i need to understand the physics behind it. I'm afraid i need Physics to do well for yr 12 but i don't understand it too well. but when i get it, i fully understand. ANYTHING, you could add would be absolutely fantastic, thanks.



___________
When all else fails, call mum!
 

beenthere

Joined Apr 20, 2004
15,819
Hi,

It's just the same effect as a moderate conductor with a potential difference across it - some current will flow.

Normally, we're poor conductors thanks to skin resistance. Sweat or a hard contact leading to a skin puncture changes this. Inside, we're a fair conductor thanks to liquids containing electrolytes like salt. I mention punctures because some years ago I was working under a car's dashboard, and a strand of wire stuck through my finger. Jolted my arm pretty good.

If you've got current flowing under the skin, then things get interesting. AC current causes ouch, but may let you turn loose. DC tends to lock muscles, and leave you hanging, so to speak. In either case, current through the heart causes abnormal beats, and can lead to death. Protected outlets trip off when they sense 20 milliamps flowing to ground (possibly through you). Hot tub protective breakers trip when they sense 5 mills. Check for voltage with a meter, not your hand.
 

Thread Starter

liv

Joined Nov 7, 2004
6
thanks


_________________________
Quidquid latine dictum sit, altum viditur


Hi,

It's just the same effect as a moderate conductor with a potential difference across it - some current will flow.

Normally, we're poor conductors thanks to skin resistance. Sweat or a hard contact leading to a skin puncture changes this. Inside, we're a fair conductor thanks to liquids containing electrolytes like salt. I mention punctures because some years ago I was working under a car's dashboard, and a strand of wire stuck through my finger. Jolted my arm pretty good.

If you've got current flowing under the skin, then things get interesting. AC current causes ouch, but may let you turn loose. DC tends to lock muscles, and leave you hanging, so to speak. In either case, current through the heart causes abnormal beats, and can lead to death. Protected outlets trip off when they sense 20 milliamps flowing to ground (possibly through you). Hot tub protective breakers trip when they sense 5 mills. Check for voltage with a meter, not your hand.
[post=3428]Quoted post[/post]​
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Steel

Joined Oct 27, 2004
25
also...

Our cells have voltage potential. They sit at -70mV and when an action potential occurs, the signal rises up (sodium/potassium exchange) to about 0 Volts.

When lightning strikes a human, it has a huge channel to flow through (our cell channels are lined with Sodium for sending action potentials), but that channel clearly can't handle the charge, and our body becomes the resistive part of the circuit.
 

Thread Starter

liv

Joined Nov 7, 2004
6
Just a quick note of thanks. There were three people that did this topic, myself and I got the highest. Thank you again,

Liv

______________
Quidquid latine dictum sit, altum vidtur.
 
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