Circuit Analysis with nodal analysis

Thread Starter

Hooperoo

Joined Apr 5, 2013
1
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
 

t_n_k

Joined Mar 6, 2009
5,455
You already know that

\(\frac{V_A-V_B}{3000}=I_1=I_4=5mA\)

So VA is of no consequence in the solution.

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