thevenin again

Discussion in 'Homework Help' started by stupid, Nov 29, 2009.

  1. stupid

    Thread Starter Active Member

    Oct 18, 2009
    81
    0
    hi,
    attached are my working. Pls verify if my answer were correct.

    first convert norton part to thevenin.
    thus the current-ctrl voltage source is 70i & 20Ω in series with the circuit.

    to compute V_{ab},
    -10 + 10i + 20i - 70i=0
    i= -0.25A

    i(20)-(70i)= -5+17.5= 12.5V =V_{ab}

    next to compute I_{sc}
    short the ab terminal,
    I_{sc}= i - 3.5i
    v=0,
    (-10+v)/10 = -i
    i= 1

    thus, I_{sc}= 1 - 3.5 = -2.5A

    hence R_{th}= 12.5/-2.5 = -5Ω

    i m wondering if i got them right.
     
    Last edited: Nov 29, 2009
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    It looks as though you forgot to attach your file?

    hgmjr
     
  3. stupid

    Thread Starter Active Member

    Oct 18, 2009
    81
    0
    i did..pls check again.
    thanks
     
  4. nirvanaguy

    New Member

    Oct 3, 2009
    15
    0
    To my knowledge you can't have negative resistance.. so maybe your current shoudlnt be negative because I'm pretty sure you got your voltage correctly
     
  5. Pinky Ringz

    New Member

    Oct 4, 2009
    6
    0
    remove the load, parallel the resistors until you get a simple series cct, reinsert the load and then calculate....no?
     
  6. stupid

    Thread Starter Active Member

    Oct 18, 2009
    81
    0
    is the shorted cct current-ctrl current source a supermesh element?
    i m lost at this.

    regards,
     
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