The discussion revolves around the nodal analysis of a circuit containing three sources and three resistors. Participants explore the identification of circuit elements, the formulation of nodal equations, and the implications of specific component values on the analysis. The conversation includes technical reasoning, potential errors in equations, and the challenges of homework problems in circuit analysis.
Participants express differing views on the correctness of the equations and the nature of the sources. There is no consensus on the resolution of the circuit analysis, and multiple competing interpretations of the problem remain.
Participants note potential errors in the formulation of nodal equations and the ambiguity surrounding the types of sources in the circuit. The discussion highlights the challenges of accurately interpreting homework problems and the importance of clear definitions in circuit analysis.
This discussion may be useful for students and practitioners in electrical engineering or circuit analysis, particularly those interested in nodal analysis and the challenges of interpreting circuit problems.
Oh yes, starting from left, first node is Va, second is Vb, third is Vc.tech99 said:
Yeah, I guess I was tired when I wrote them and didn't copy some stuff correctly.DaveE said:
Ooooh, yes you're right, I completely missed that, thank you.DaveE said:
You mean the right most node, don't you?DaveE said:
Oops! No, I meant the leftmost source ##0.02v_1 = 0 ##, since ##v_1=0## . This is because the rightmost source equals the current across the top.The Electrician said:
Yes, exactly, that's why I wouldn't choose this as a HW problem. It's not great learning for working in the real world, where tricks rarely work this well.The Electrician said:
Are you asking me to solve this for you? You first; then I'll help if you get stuck.The Electrician said:
The middle source has to be a voltage because if it's a current source there would be 3 current sources feeding a floating object (3 resistors in a delta configuration) from which there is no return path to ground, and the voltage of that object would be indeterminate. If the middle source is a voltage source, then at least the voltage(s) of the floating object won't be indeterminate.DaveE said:
Yes. Although since they only asked about ##i_2##, the question is solvable. It's a case of infinite vs. a single solution.The Electrician said:
Actually, no I don't. Perhaps I should. But I've done enough in the past and, honestly, it's a pretty rote application of network analysis. Something has to make me interested first, then I'll solve it, right up until the point that I lose interest. *The Electrician said:
Xaio Xaio, DaveE showed you a trick that gets you the right answer, but the problem requires you to find the solution using nodal analysis. Your nodal equations have errors. Will you be working on this problem's nodal analysis any more?Xiao Xiao said:
Yes, these are my equations so far.The Electrician said:
Your 3rd equation doesn't look like a proper nodal equation. Can you write in the proper form? If you do, do they have a solution?Xiao Xiao said:
The third one should be ##(v_b-v_c)/2+0.2v_3=(v_c-v_a)/2##The Electrician said:
Nothing elseBvU said:
The resistor is in place of the right current source.Xiao Xiao said:
Yeah it's completely messed up, and I couldn't figure on what basis they changed the question. So I'm sticking with the solution that I ended up with in my previous reply.The Electrician said:
Has your professor responded yet? What did he say?Xiao Xiao said:
No he did not, unfortunately. So I asked him about the solution in hope he respond, if he uploads the solution for the question later (because this was in our assignment) or answers my question, I'll update with the righ question or method to use here.The Electrician said:
