Mesh Current Analysis Problem Help

Discussion in 'Homework Help' started by crazyengineer, Dec 31, 2010.

  1. crazyengineer

    Thread Starter Member

    Dec 29, 2010
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    [​IMG]

    Hi I need some help trying to solve IO in this mesh current analysis problem. Element E is a 5 volt power supply with the + at the top. What I originally did....

    Set mesh 1 (ia) in the left loop as

    10=5000ia-10000ia+10000ib

    and mesh 2 (ib) in the right loop as

    5=10000ia-10000ib-4000ib

    after algebraic manipulation I found ia=.004167a and ib=.006333. Then I subtracted ia from ib and thought io=-.002167. However, the book's answer was -.136ma. Please help!
     
  2. kira12a8

    New Member

    Dec 31, 2010
    2
    1
    Your equation is wrong man. It's must be :
    15000Ia - 10000Ib = 10
    -10000Ia + 14000Ib = 5

    Calcultes it then substracts you will get the right answer -136mA :D
     
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  3. Jony130

    AAC Fanatic!

    Feb 17, 2009
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  4. crazyengineer

    Thread Starter Member

    Dec 29, 2010
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    hmmmm I understand how mesh b is -10000Ia + 14000Ib = 5, but I'm puzzled about how mesh a is 15000Ia - 10000Ib = 10. Isn't the it -5000ia+10+10(ia-ib)?
     
  5. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    I like to write it in this way
    -10 - 10000 (Ia - Ib) - 5000 Ia = 0
    -4000Ib - 5 - (Ib - Ia) 10000 = 0

    Io = - 3/22000 = 136.363636uA
     
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  6. crazyengineer

    Thread Starter Member

    Dec 29, 2010
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    Hmmm. I'm sorry if I'm still asking questions about this problem, but I want to fully understand this method.

    From what I read, I thought that traversing the loop should be in a clockwise direction, so I thought that it would be -5kia since it's going negative to positive, then 10v since it's going positive to negative then positive 10k(ia-ib) since it's going positive to negative.
     
  7. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    Read the link I post
    "The choice of each current's direction is entirely arbitrary"
     
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  8. crazyengineer

    Thread Starter Member

    Dec 29, 2010
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    OOO! I see now. Thank you everyone!
     
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