Circuit Analysis with nodal analysis

Discussion in 'Homework Help' started by Hooperoo, Apr 5, 2013.

  1. Hooperoo

    Thread Starter New Member

    Apr 5, 2013
    Hi guys.
    Im tearing my hair out over this problem, so any help would be greatly appreciated.


    Im solving the circuit with nodal analysis, and following the steps of:
    1: Ground node equation
    2: Voltage source and current source equations
    3: Equations for each resistor
    4: KCL at each node apart from the ground node
    5: Substituting resistor equations into the KCL equations and solving for the node voltages
    6: Solve for branch currents
    7: Find power consumed or supplied

    The problem is, i get to step 5, find a node voltage, but apparently it's the wrong answer. It doesn't match any of the answers supplied by the teacher (it's a practice multiple choice exam).

    Attached is my working, with a picture of the circuit.

    I get to a voltage for node B (circled in red), however, when I sub this in to find the voltage at node A, i get the wrong answer (12.8).

    Please please please tell me what I am doing wrong.

    Thank you in advance
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    You already know that


    So VA is of no consequence in the solution.

    You then only have to find VB given VC is also known.