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Electical shock, electrocution questions

  1. Jan 26, 2008 #1
    HI, I couldn't decide which forum was the best to post these in. I have two questions regarding electricity and getting shocked, or electrocuted.

    1. Being shocked from the spark plug leads on either small engines (lawnmowers) or cars. Classically, on either of these, you have a coil which acts as a transformer to kick the voltage up to approximately 10,000 to 20,000 volts needed to force a spark to jump the sparkplug gap. THe current is relativley small. Touching the spark plug leads while this voltage is present will give you a good jolt, but is far from life threatening, I assume because the current is low. My question is, if you only contact the voltage at one point on your body, ie hand, are wearing shoes with thick soles, have no part of your body completing a circuit back to ground at the car or engine, (your body is not completing a circuit) then why do you get shocked?

    2. Household AC power , say 110volts. Say you introduce this into a swimming pool of water (10 feet deep) that someone is swimming in by dropping a radio or other appliance into the water that is on and plugged into a household outlet. Say the person is 6 or 7 feet from the radio in the water, and the water contains enough minerals to conduct electricity to some degree. Assume the person is not touching anything but water. I don't see why the person would be electrocuted, because I can't see how they complete a circuit for the electricity. I would think it would seek ground via the radio itself and throw the breaker at the house. That being said I have no intention of conducting such an experiment on myself or anyone else for that matter lol.

    John
     
  2. jcsd
  3. Jan 26, 2008 #2
    1) I'm not sure if this is the best answer, but air is a much better insulator than your body and your hand, so even a convoluted route through you and back out the other half of your finger will have less resistance than a path through only the air.

    2) If there is a drain in this pool, and the ground of the radio is well insulated, then you would have a voltage difference between the drain and the radio, but the circuit breaker wouldn't be thrown. If there is enough chlorine in the pool to make its resistance low enough, and you just happen to be between the radio and the drain, you could be electrocuted.
     
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