Please help!

Discussion in 'Homework Help' started by xnager23, Sep 20, 2007.

  1. xnager23

    Thread Starter New Member

    Sep 20, 2007
    1
    0
    Hello,

    For the attached circuit i have to find the current through each resistor using 3 methods: mesh, node voltage, and superposition.

    For Mesh Method:
    I1: clockwise in square ABFD
    I2: counterclockwise in square CBFE
    I3: clockwise in DFE

    Formulas used:
    Mesh 1: 10 = 7(I1)+2(I2)
    Mesh 2: 20 = 2(I1)+9(I2)+4(I3)
    Mesh 3: 0=-4(I2)-6(I3)

    From this i get currents of I1=0.579A, I2=2.975A, I3=-1.983. I then use these to find values of current over each resistor.

    Now when i try the node voltage method i am supposed to get the same current across each resistor but i do not.

    The equations i have for the node voltage method are(# by I is resistor):
    I1=(Va-Vb)/R1
    I2=(Vf-VB)/R2
    I3=(Vb-Vc)/R3
    I4=(Ve-Vf)/R4
    I5=(Vd-Ve)/R5
    Vc=20-Ve
    Vd = Vf = Ground = 0 V
    I1+I3=I2 at Node B (using KCL)
    I2+I5=I4 at Node F (using KCL)

    When using these equations i do not get the same values of I for each resistor as in part 1.

    For superposition method, i have no clue on how to reduce the circuit to one equivalent resistor for each of the power sources seperately.

    Please, any information/help would be appreciated!!!
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,136
    1,786
    Please construct a more informative title. I won't give a useful response to a useless title.
     
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