Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Parallel circuit with humans

  1. Apr 30, 2007 #1
    Here's an episode of brainiac, where they test how much an
    electric fence is shocking:

    Now at time index 2:21 they build a parallel circuit with humans.
    What I wonder about is why only the first two persons get strong shocks,
    while the others don't. Can anyone explain this?

    They also form a series connection at time index 4:20. The shock gets straight to the end.
  2. jcsd
  3. Apr 30, 2007 #2
    I watched the whole thing, pretty cool.

    The circuit formed by these people wasn't really parallel. Think of the arms and legs as resistors. By holding hands, they formed a chain of resistors in series and at every junction forming parallel resistors by legs to ground.

    So it makes sense the first person would receive the most current.

    Now at the end, they insulated their legs. So the circuit was a just in series where current passes through them all.
  4. May 2, 2007 #3
    I see now that it's not a pure parallel circuit.
    Though I still have to think about why the first person gets the strongest shock by examining the circuit.

    Thanks for you answer.
  5. May 2, 2007 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    They even describe why the first guy gets shocked the most. The electricity starts flowing through the first guy, and some of it goes through the first guy to the second one, while some of it goes through the first guy to the ground.. So that guy gets the whole amperage through his body. The next one gets, maybe, half the amperage. Half of that goes to the ground, half goes to the next one. So the third person gets 1/4th the current
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook