What is Nodal analysis: Definition and 176 Discussions

In electric circuits analysis, nodal analysis, node-voltage analysis, or the branch current method is a method of determining the voltage (potential difference) between "nodes" (points where elements or branches connect) in an electrical circuit in terms of the branch currents.
In analyzing a circuit using Kirchhoff's circuit laws, one can either do nodal analysis using Kirchhoff's current law (KCL) or mesh analysis using Kirchhoff's voltage law (KVL). Nodal analysis writes an equation at each electrical node, requiring that the branch currents incident at a node must sum to zero. The branch currents are written in terms of the circuit node voltages. As a consequence, each branch constitutive relation must give current as a function of voltage; an admittance representation. For instance, for a resistor, Ibranch = Vbranch * G, where G (=1/R) is the admittance (conductance) of the resistor.
Nodal analysis is possible when all the circuit elements' branch constitutive relations have an admittance representation. Nodal analysis produces a compact set of equations for the network, which can be solved by hand if small, or can be quickly solved using linear algebra by computer. Because of the compact system of equations, many circuit simulation programs (e.g., SPICE) use nodal analysis as a basis. When elements do not have admittance representations, a more general extension of nodal analysis, modified nodal analysis, can be used.

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  1. A

    Did I do the nodal analysis right?

    can someone confirm i did this rite: Homework Statement Find I(x) Homework Equations see the next part please The Attempt at a Solution using nodal analysis method i have 2 nodes and these are the equations i got for each, after simplification: V1: (5/2)V1-V2=21 V2: (5/2)V2-V1=10.5 Using...
  2. C

    Find the voltage Vm (mesh / nodal analysis)

    Homework Statement http://img541.imageshack.us/img541/5039/homeworkprobsg27.jpg Find the value of the voltage Vm Homework Equations V = IR, KVL, KCL, mesh equations, nodal equations The Attempt at a Solution...
  3. N

    Nodal Analysis question me

    Homework Statement Using Nodal analysis, determine the current through each resistor, for this circuit. Could you please show the KCL working out.I need the answers Please help me i am helpless with nodal analysis consist of a current source.Thanks in advance :) !.please help me. r1=120...
  4. M

    Engineering Having trouble with some review circuits using nodal analysis

    Having trouble with some review circuits using nodal analysis :( Homework Statement I'm trying to find node voltages for v1, v2, and v3. I = 3.1A Homework Equations V=IR The Attempt at a Solution My method of going about and solving this was fairly straight forward I thought...
  5. G

    Engineering Nodal Analysis on Electrical Circuit

    Homework Statement The Attempt at a Solution According to the similar problem Node X: I1=(22-Vx)/66 I2=(66-Vx)/44 Il=Vx/264 I3=I1+I2+Il Node Y: I4=Vy/240 I5=6 I4=I3+I5 After the calculations I get 1.08 for Vx, which I think is wrong. Thanks
  6. C

    Find Io in the network nodal analysis

    "Find Io in the network" nodal analysis Homework Statement http://img189.imageshack.us/img189/8807/homeworkprob22.jpg Find Io in the network Homework Equations V = IR current division, voltage division, KCL, KVL Nodal Analysis (or mesh)The Attempt at a Solution So I think I need to use...
  7. T

    Why is my circuit nodal analysis not giving the correct I_sc value?

    Homework Statement The Attempt at a Solution Essentially I am having trouble with solving for I_sc when I remove the load and replace it with a wire. I used a super node at 1 and 4 and also in my diagram I have defined the currents with directional arrows. I have been on this question for a...
  8. JJBladester

    Mesh and Nodal Analysis - Source Frequency

    Homework Statement Mesh and nodal analysis are used to find unknown currents and voltages in planar networks. Why is it necessary when performing these network analyses that all of the source frequencies be the same? The attempt at a solution I know that superposition let's us analyze...
  9. J

    Electrical nodal analysis, find current

    Homework Statement ive tried many things and can't seem to grasp the concept of KCL.i know the node I am looking for is between r1 & r3. i assumed i1+i2=i3. also looking for directions of currents. V1=30v V2=40v R1=82 R2=68 R3=47 Vx = ?Homework Equations i1 + i2 + i3 = 0 ? The Attempt at a...
  10. M

    Nodal analysis: simple confusion

    My question about this excercise is the 80+20 part in the denominator. Why and when do I do that? I tried doing it but got the wrong answer
  11. A

    Engineering Nodal analysis for OP amp circuit using superposition

    Homework Statement http://www.wifstrand.se/Albert/stuff/p6.5-9.png I'm stuck with finding v_o1 (voltage over the 10kohm resistor when all sources but the 3 V source, which I've labeled v_1, is set to zero); seems like it should be really simple but I'm missing an equation. Homework...
  12. D

    Which Approach is Correct for Nodal Analysis in Electricity Books?

    In nodal analysis method, two books use different and contradicting approaches and not sure which one is correct. One books says that currents at each nodes should be treated independently from the other nodes so that the same current can have two opposing directions in the same equations. The...
  13. C

    Engineering Circuit Nodal Analysis: Writing Node Equations

    Homework Statement a)Write two node equations in terms of the literal variables. I1 = Is1 I2 = gm2Vo I3 = gm1Va I4 = Is2 Va = Voltage across R2 Vo = Voltage across R1 Vb = Voltage across R3 Homework EquationsThe Attempt at a Solution I tried setting up nodes right above R2 and Right above...
  14. L

    Find V0 in Nodal Analysis Problem with Annotated Circuit and Equations

    I need to find V0 in the given circuit. I've uploaded both the problem, and an annotated one with the variables I chose. These are the equations I got for the system: V_{0}=30-V_{2}-V_{3} V_{2}=30-i_{1}(10\Omega ) V_{2}=I_{X}(2\Omega ) V_{3}=30-V_{2}-(-i_{1})(1\Omega )...
  15. Q

    Finding Vx with Nodal Analysis in a Circuit with Multiple Voltage Sources

    Homework Statement I have to use Nodal analysis to find Vx Homework Equations our prof said that if we want to find the number of unknowns and eqxns necessary then we need to find all the nodes in circuit - the reference node - number of voltage sources, for this circuit that would be 4...
  16. A

    Solve Nodal Analysis Circuit: Find Voltage in All Nodes

    I need to solve this circuit using nodal analysis (find the voltage in all nodes), but i need the actual equations used to solve it. http://dl.dropbox.com/u/202411/p2/circuit328.png All supplied information is there. What I've done is to create 2 supernodes, like this...
  17. N

    Nodal Analysis - KVL Loop question.

    Homework Statement I've obtained the node equations that's in the matrix for rows 1, 2, and 4. I got 3 as well but I'm not sure if my analysis was correct. http://img252.imageshack.us/img252/3151/nodeq.jpg The Attempt at a Solution http://img684.imageshack.us/img684/9803/dsc0010van.jpg So...
  18. E

    Nodal analysis with parallel resistors

    I'm trying to determine v,oc using nodal analysis. I have labeled the two node voltages at the top v,1 and v,2. When doing the KCL equation for node voltage 2, I run into the 1.1 kohm and 2.3 kohm parallel combination. Is it valid if I just combine these parallel resistors into one resistor?
  19. N

    Nodal Analysis Question - Find the Node Voltages

    Homework Statement http://img12.imageshack.us/img12/6886/nodalanalysisproblem.jpg The Attempt at a Solution I put in the currents for KCL in the diagram, though I'm not sure if I've done it right. So essentially I get the equation as i1 + 3 = i2 + i3 Current in = current...
  20. genxium

    Question about Nodal Analysis of non-linear component

    When I'm reading a tutorial about Harmonic Balance algorithm (this is a link to the tutorial website), I'm quite confused by the concept it mentions about the nodal analysis of non-linear components, especially for: The non-linear circuit is modeled by its current function i(t) = i(v_1...
  21. S

    Nodal Analysis and Power Balance in AC Circuits

    I'm working on an ac circuit, and we were told to use nodal analysis. Furthermore, we are asked to show a power balance between the sources and the power dissipated in the resistors, along with a reactive power balance between the sources and the inductors and capacitors. I have this formula...
  22. M

    Nodal Analysis (KCL): Correct My Equations

    For the following circuit, can someone please correct my equations for nodal analysis (KCL) I am especially unsure about my second equation because of the dependent voltage source to the left of the node. 1) I1 = (V1 - 3I2)/1 2) 0 = V3/2 + (V3 -V2)/2 3) I2 = (V2-V3)/2 + 2V3
  23. J

    Kirchhoff's current law and nodal analysis

    Hello, I'm looking to work out the current at I in the following circuit using Kirchoff's current law and nodal analysis: [PLAIN]http://img853.imageshack.us/img853/4792/circuitgem.jpg Using Kirchoff's voltage law (and loop analysis), I got a current of (35/22)A, but for the current law...
  24. N

    Can someone please explain the solution to a nodal analysis problem to me?

    Homework Statement Homework Equations V=IR, Nodal Analysis The Attempt at a Solution 1 and 2 in the diagram are the nodal equations. Considering that the left node is V1 and that the right node is V2. I don't know how to get from the nodal equations to step 3. I know that you go...
  25. N

    Need help with Nodal Analysis. I have the work, just need a step explained.

    Homework Statement Homework Equations V=IR, Nodal Analysis The Attempt at a Solution 1 and 2 in the diagram are the nodal equations. Considering that the left node is V1 and that the right node is V2. I don't know how to get from the nodal equations to step 3. I know that you go...
  26. N

    Can someone please explain a step to a solution? It's about nodal analysis

    Homework Statement Homework Equations V=IR, Nodal Analysis The Attempt at a Solution 1 and 2 in the diagram are the nodal equations. Considering that the left node is V1 and that the right node is V2. I don't know how to get from the nodal equations to step 3. I know that you go from step...
  27. N

    How to Use Nodal Analysis for Circuit Analysis?

    Homework Statement Homework Equations nodal analysis The Attempt at a Solution When i did the problem, i got 3V. Is this right or wrong?
  28. N

    Can someone please check my signs on this Nodal Analysis

    Homework Statement Homework Equations Nodal Analysis, KVL The Attempt at a Solution
  29. V

    Apply Nodal Analysis to the Circuit

    Homework Statement Apply nodal analysis to the circuit to find the power (released or absorbed?) by the 3-mA source. [PLAIN]http://img15.imageshack.us/img15/1546/circuity.png Homework Equations Ohm's Law V = IR The Attempt at a Solution OK, so firstly I have to label all the...
  30. N

    Help figuring out nodal analysis

    Homework Statement Homework Equations Equivalent resistance? Nodal analysis? V=IR The Attempt at a Solution I was thinking of using nodal analysis at the points designated by the arrows. The bottom one would be connected to ground. My question is if I picked out the nodes...
  31. PainterGuy

    Nortonization and nodal analysis

    Hi, :) Please have a look on the following link: http://img836.imageshack.us/img836/1554/circuitmm.jpg 1: I was trying to solve a circuit. I was successful except the part where I was trying to apply the nodal analysis (it's at the very end of the linked scan). Where am I going wrong? By nodal...
  32. E

    AC Nodal Analysis Adding source phase angles AFTER calculation?

    Just to clarify the title... Basically for the below circuit we are required to find Vth, Rth and Vo. However, the method of solving this problem is a little strange to me, because as you can see, the source has a phase angle of 30 degrees. The solution to this problem basically says (to find...
  33. PainterGuy

    Help with this simple nodal analysis issue, please

    Hi, :) 1: http://img19.imageshack.us/img19/2256/nodaldiagram1.jpg (diagram of circuit and few other details) 2: http://img36.imageshack.us/img36/5405/nodaldiagram2.jpg (solution) The book asks "Find the magnitude and polarity of the voltage across each resistor". I was trying to find...
  34. PainterGuy

    Simple application of nodal analysis

    Hi, :smile: Almost all the details you will find in the given link below: http://img710.imageshack.us/img710/1565/exampleproblemnodalysis.jpg You will find the expected (or, target answers) in the top right corner. As you can see my value for V1 is utterly wrong. It should have been...
  35. PainterGuy

    Engineering Applying nodal analysis on this simple circuit

    Hi, :) Almost all the details you will find in the given link below: http://img171.imageshack.us/img171/9797/nodalysis1.jpg You will find the expected (or, target answers) in the top right corner. As you can see my value for V1 is wrong. It should have been 80V according to the answer...
  36. E

    Nodal Analysis with power supplied to capacitor

    Homework Statement Following circuit has v=30v, r1=20ohm,r2=10ohm,r3=15ohm. A)Determine inductor current (I) and capacitor voltage (Vc). B)Determine power supplied by source before switch is open. Homework Equations KCL P=VIThe Attempt at a Solution I attempted to treat the load plus the...
  37. J

    Engineering Badic Circuit - Nodal Analysis

    Basic Circuit - Nodal Analysis Homework Statement I am trying to find ix and iy. Here is the figure http://tinypic.com/view.php?pic=x2mr93&s=7 The Attempt at a Solution Node 1 -3 + V1/0.2 + (V1-V2/0.5) = 0 -.06 + 0.1V1 +0.2V1 - 0.2V2 =0 -.06 + 0.3V1 -0.2V2 = 0...
  38. B

    Nodal Analysis w/ Controlled Sources

    Homework Statement Find V1, V2 and V3. Homework Equations Nodal Analysis Supernode Equation Capacitance = 1/R KCL & KVL The Attempt at a Solution KCL @ node 0: Ic = v2(-G1) +v3(-G3) Node 1: Ic + I1 +v3(G2+G3) +V2(-G3) = 0 (subbing in Ic) v2(G1+G3) + v3(g-3) = I1....Equation (1) Node 2...
  39. P

    Troubleshooting Nodal Analysis for a 2 PSU Resistor Circuit

    Homework Statement see attached Homework Equations The Attempt at a Solution Hey, I'm having trouble with a 2 PSU resistor NA circuit. here is what I've done: N1=V1 N2=v2 N3=v3 = 0V N4=v4 0=(10-v1)/4K7-V2/10k-(V1-V2)/1K 0=(V1-V2)/1K-(V2-V4)/470-(V2-V4)/1K...
  40. P

    How Do I Correctly Apply Nodal Analysis in This Circuit Problem?

    Homework Statement See attached picture. Homework Equations The Attempt at a Solution I really suck at this and am having trouble understanding the textbook we have. here's my attempt: I'm calling node 1 v1 and 2 v2. so 0=(v1-v2)/4k7+v1/10k+(v2-v1)/1k 0=(v2-v1)/1k+v2/470+v2/1 I know I have...
  41. M

    Modified nodal analysis with Voltage Controlled Voltage Source

    hi, i got a question about mna. i know how to write matrixes with(out) voltage source but i don't know what i should do when my instructor askes me placing vcvs or vccs instead of any resistor. i have lecture notes for vcvs ust like; Vpq=u(mu)*Vkl i should add extra rows and cols. to matrix of...
  42. P

    How Accurate is the Calculated Current I_b Using Nodal Analysis?

    Homework Statement Determine I_b in the circuit below using nodal analysis. http://img8.imageshack.us/img8/1339/circuit39.th.png Homework Equations Ohms LawThe Attempt at a Solution Can someone tell me if i have done anything wrong in my first part of the question. Becuase i am pretty sure...
  43. C

    Solving Circuit Equations with Mesh and Nodal Analysis

    Homework Statement The circuit shown has two inputs, V_{s} and i_{s} and one output V_{o}. The output is related to the input by the equation V_{o}=ai_{s}+bV_{s} where a and b are constants to be determined. determine the values a and b by (a) writing and solving mesh equations and (b) writing...
  44. M

    Nodal Analysis Review Requested: Help Matt Out!

    Homework Statement Im tring to apply nodal analysis on the following, and would like to know if i have done this correctly. Can someone please review it. [PLAIN]http://img121.imageshack.us/img121/5573/lastscanq.jpg Thank you for your time. Matt
  45. T

    Engineering Find v in electric circuit (nodal analysis, superposition)

    Homework Statement Find the voltage v across the 5 Ohm resistor as shown in the attached drawing. Homework Equations Ohm's law, V=IR The Attempt at a Solution I have done plenty of these using different techniques, superposition/source transformation, nodal or mesh analysis, etc...
  46. J

    Solving Nodal Analysis: Find V1 and i1

    Homework Statement Find V1 and i1 using nodal analysis The Attempt at a Solution I know i1 is 0 because of a circuit break. But, I am not able to figure out how many nodes there are in this circuit? I thought there are four nodes connected to the reference point but the book...
  47. N

    Confused about KCL & Nodal Analysis (basic stuff )

    Homework Statement I'm confused about how to use KCL when doing Nodal Analysis. Please consider the diagram below: http://img27.imageshack.us/img27/4900/20091019131641633915550.jpg Homework Equations My first point of confusion is that the diagram shows the current "4Ix" going up...
  48. G

    Nodal analysis, setting up the equations

    Homework Statement [PLAIN]http://img844.imageshack.us/img844/8508/circuit.png Homework Equations KCL set ups The Attempt at a Solution I am having trouble setting up the KCL equations The 30V voltage source on the left with the resistor is messing me up, how do I incorporate...
  49. R

    Solving Nodal Analysis with a Circuit Diagram

    [PLAIN]http://img707.imageshack.us/img707/2437/elect2.png I'm just wondering where I have to put the reference node in this circuit when doing nodal analysis.
  50. G

    Nodal analysis physical problem

    in the nodal analysis -one of ways of analysis DC circuit - i couldn't understand the physical roots of this way . i mean how could i make the voltage of a node equal to zero by make it as a reference point without having any effects on the voltage(electric potential) of the rest nodes ...
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