help?

Discussion in 'General Electronics Chat' started by liv, Nov 7, 2004.

  1. liv

    Thread Starter New Member

    Nov 7, 2004
    6
    0
    :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!
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    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.
     
  3. liv

    Thread Starter New Member

    Nov 7, 2004
    6
    0
    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]​
    [/quote]
     
  4. Steel

    Member

    Oct 27, 2004
    25
    0
    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.
     
  5. liv

    Thread Starter New Member

    Nov 7, 2004
    6
    0
    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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