Equivalent Resistance with Wye Delta Help

Discussion in 'Homework Help' started by rodhdanan, Jun 4, 2014.

  1. rodhdanan

    Thread Starter New Member

    Jun 4, 2014
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    I have tried numerous ways to solve both these problems but i keep getting crazy numbers that in no way could be right. can somebody please tell me how to do these step by step? i know wye delta is involved but somehow im messing up the math.

    Attempt at solution:
    I made the 3-6-12 delta into a wye but that gave me crazy numbers that ended up being even crazier at the end.

    in the second one i tried making the 2-9-20 delta into a wye and met similar problems as i did in the first one

    Problems:
    http://tinypic.com/r/28gv0ap/8

    thank you for any help
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    For the second one I got 11 Ohm. Straight up parallel and series resistors, no delta-to-y transformations.
     
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  3. rodhdanan

    Thread Starter New Member

    Jun 4, 2014
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    Guess I overcomplicated the second one. I got 11 Ohms also when I tried straight parallel and series. Can't see anyway to do the same on the first one though. The cross section is tripping me up.

    EDIT: Got it now. Was not taking into account the semicircle in the cross section. Can someone confirm the answer is 11.2 Ohm?
     
    Last edited: Jun 5, 2014
  4. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    The crossover is a distraction intended to test your powers of observation. A little thought should allow you to conclude the 3Ω & 6Ω are simply in parallel as are the 4Ω & 12Ω. Does that clarify anything for you?

    No transformation is required.
     
  5. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    Yep, I just saw that. I will delete my earlier post.
    Edit.
    Ok, I got 11.2 Ohm for the first one.
     
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