Discussion in 'Homework Help' started by kana, Oct 10, 2004.

  1. kana

    Thread Starter New Member

    Sep 19, 2004
    hello guys
    please i need help in this circuit as soon as possiable .... plz !!

    :( :( :unsure:

    i dont know how to solve it
  2. Battousai

    Senior Member

    Nov 14, 2003
    First of all, what are you solving for?

    There are four nodes: one on the left, one in the middle, one on the right, and ground (bottom).

    But essentially you can treat the nodes in the middle and on the right as a single "supernode." With Vright = Vmiddle + Vs2 (eq1)

    Now just use Kirchoff's Current Law (KCL) to write equations to determine the desired unknowns.

    KCL states that "all current entering a node must sum to 0"

    So using Ohm's law, I=V/R

    The current entering the middle node from the left node is:

    Ileft = (Vleft-Vmiddle)/R1 (eq2)

    The current entering the middle node from ground is:

    Iground = (0-Vmiddle)/R2 (eq3)

    And finally, the current entering from the right-most node is:

    Iright = (0-Vright)/R3 (eq4)

    Applying KCL: Ileft+Iground+Iright=0 (eq5)

    Also we know Vleft=Vs1.

    Now you have five equations and five unknowns... so solve.

    Hope this helps.