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Homework Help: Short circuit confusion, when is the resistance 0

  1. Dec 7, 2017 #1
    1. The problem statement, all variables and given/known data

    I'm going exercises and I understand that if the circuit is short circuited that R=10 ohm is 0. (Trying to find Thevelin R in all of these btw)
    upload_2017-12-7_22-18-11.png
    But then I ran across this one where when it's short circuited, isc is found using the current divider principle and it's R1/(R1+r2), why doesn't R1 turn to zero?

    upload_2017-12-7_22-18-58.png
     

    Attached Files:

  2. jcsd
  3. Dec 7, 2017 #2

    phinds

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    Gold Member

    Is R1 in parallel with the short?
     
  4. Dec 7, 2017 #3
    Yes.....? If there's a resistor in between does that make them stop being in parallel?
     
  5. Dec 7, 2017 #4

    phinds

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    Gold Member

    I suggest that you go back and study over and over the fundamentals of series and parallel. You HAVE to get that totally straight before trying ANY circuit problems and you have some confusion.
     
  6. Dec 8, 2017 #5

    gneill

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    Staff: Mentor

    Yes. If you can't follow a closed path passing through the two components that does not have to pass through any other component along the way, then they are not parallel-connected. Put another way, if two components are parallel-connected, then you can draw a closed path that passes only through that pair of components.

    upload_2017-12-8_10-24-10.png

    upload_2017-12-8_10-24-41.png
     
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