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Math Help - Short circuit question

  1. #1
    Forum Admin topsquark's Avatar
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    Short circuit question

    I had a student ask me this question. I have never seen two sources connected in parallel quite like this so I thought I'd see if anyone with more knowledge about circuitry could verify my thoughts.

    The parallel combination of sources sets up a short-circuit in the system, with a "back" current balancing out to produce an overall 3 V potential across the resistor.

    Obviously in reality the sources have internal resistance and the problem is easily solvable. It's the zero internal resistance case I am curious about.

    -Dan
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    Quote Originally Posted by topsquark View Post
    The parallel combination of sources sets up a short-circuit in the system, with a "back" current balancing out to produce an overall 3 V potential across the resistor.
    I did not understand the "back" current idea, can you please elaborate?
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  3. #3
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by Isomorphism View Post
    I did not understand the "back" current idea, can you please elaborate?
    My thought is that the 5 V source will cause a current in the 2 V branch in the "wrong" direction. (That's what I'm calling a "back" current.) Normally when this happens we have an effective cancellation of the 2 V potential leaving a leftover of an effective 5 V - 2 V = 3 V potential over the parallel combination. (I think I'm remembering that right.)

    -Dan
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