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Homework Help: A Question about Series-Parallel Circuits

  1. Oct 21, 2013 #1
    Hello Guys !!

    In This photos i found that
    in (a) : RT= 4 Ω+ 10 Ω+ 4 Ω= 18 Ω
    in (d) : RT= 10 Ω

    but i can't understand why in (a) the total resistance equals to 18 and how will the current would pass ??

    and in (d) i can't understand why the total resistance equals to 10 and why we didn't take the two 4 ohm resistances in the count ?!!



    Thank you Guys !! :))
  2. jcsd
  3. Oct 21, 2013 #2
    Current can flow only in close loops so for example A

    In circuit D you have a short wire. And all current will flow through shorted wire.

    Attached Files:

  4. Oct 21, 2013 #3
    why not R=4+4=8Ω ??

    Attached Files:

  5. Oct 21, 2013 #4


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    Staff Emeritus
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    What is in parallel with those 2 resistors? What is the resistance of a wire? How do you find the resistance of a parallel network?.
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