# What is Node analysis: Definition and 26 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. ### AC - Node Voltage Method for difficult circuit

Hi! I'm trying to understand and solve this circuit by Node Voltage Method. I have to calculate u(t). In my mind, I don't have any idea if any current should go through Z1 in my calculations. I would be grateful if you could write even equations for this circuit. Is 'a' just a prefix to multiply...
2. ### Solving a circuit using both the mesh and node analysis

Homework Statement The problem asks to solve for i1, i2, and i3 using the mesh method in the following circuit: I will also include the link, because I noticed I am having trouble attaching the image to the post: https://imgur.com/a/bBvuLXM I would also like to confirm the answer by solving...
3. ### Help with Node Analysis Circuit Problem

Homework Statement I have a circuit which I have a current through labelled I on circuit. I have -9.18 +j17.31. we agreed this was correct. I have a node analysis problem but cannot find the correct answer. I feel my method and my maths may be off but would like some advice if possible...
4. ### Circuit with two voltage sources, finding voltage at nodes

Okay, so why is it that Vc assumed to be 12v - 0.7v (D1), how about contribution from the 9v battery?? Why is this not affecting the voltage at node C? Why Vc isn't 9v - 0.7v (D2) = 8.3v?
5. ### Is Vb 0V in this Op-Amp circuit?

Homework Statement I am wondering if in this circuit Vb will be 0V? Homework EquationsThe Attempt at a Solution I have found all the other ones, but I am unsure if Vb will be 0 or not, and if it is then what is the logic behind it?
6. ### Super Node Analysis: Find V1,V2,V3,I1,I2,I3

Homework Statement Find V1,V2,V3,I1,I2,I3 Homework EquationsThe Attempt at a Solution Analysis at super node: V3-V1=40 (equation 1) (V1/40)+(V1-V2/40)+(V3-V2/20)=0 2V1 - 3V2 +2V3 = 0 After substituting in equation 1: 4V1-3V2 = -80 Analysis at V2 (V1-V1/40)+(V2/20)+(V2-V3/20)=0 After...
7. ### Nodal analysis, choosing reference node confusion

I know that when we have to identify the nodes for solving a circuit with nodal analysis we always have to designate a reference node (which will be the ground node) as a reference for measuring the others' voltages. However I was practicing this and I found this example on...
8. ### Nodal analysis, choosing number of nodes confusion

Good evening people. Recently I started taking the "electric network analysis" course in my school. We already saw the mesh analysis method for solving circuits. Now we are seeing the node analysis method. I understand that the first step for this method is finding the number of nodes (and one...
9. ### Question about mesh and node analysis

Hi, I'm trying to figure out if I haven't undestood the correct way to do a circuit analysis yet, or if I am just mistakening my calculi. Here is a scheme of the circuit: The component in the right bottom angle is a voltage dependent voltage source controlled by V0. I tried to make a mesh...
10. ### Circuits - Node analysis of connected and dependent sources

Hey! I have a problem with the theory side of this circuit here: 1. The problem I know that you are supposed to pick the buttom node of the circuit to represent your significant node at which you shouldn't construct a series of equations. But what if I picked another node as my significant node...
11. ### Engineering Solving a Node Analysis Problem with 0.632V Voltage Source

Homework Statement Attached image Using node analysis: ix(0-) = (v-4)/10 + v/3 + v/5 = 0 v = 0.632 ix(0-) = -v/3 = -0.211 A I don't understand why they didn't use a current divider since there is a 5 ohm resistor in parallel with the 3 ohm. Current changes for resistors that...
12. ### Mistake in this node analysis work?

Is the working out for node V2 wrong? In particular, I am referring to the (V1-V2)/2 term in equation 2? Also, is the voltage drop always in the same direction as the current or is the voltage rise always in the same direction as the current? Thanks
13. ### Grounding Node Analysis: Understanding the Basics

Why does node analysis have a ground node?
14. ### Node Analysis Help: Troubleshoot Your Homework

Homework Statement Homework Equations The Attempt at a Solution At node 1: (V1-10)/5 -2 + (V1-V2)/4 = 0 --> 9/20V1 - V2/4 = 2 At node 2: (V2-V1)/4 + (V2 - 4*I)/6 + V2/2 = 0 and i use also I= V2/2 i get V1=5.83V and V2=2.5V but its not the rite answer. what am i diong wrong??
15. ### Node Analysis for LM2577 Block Diagram

Greetings Members I'm a chemistry student doing some research [this is not homework!] on boost conversion and I need help discerning the node analysis for this step-up voltage regulator. I've found pretty decent tutorials on elements such as the comparator, npn transistor, and oscillator. But...
16. ### Solving a Complex Circuit: Loop Analysis & Node Analysis

Homework Statement [PLAIN]http://img856.imageshack.us/img856/8508/circuit.png Homework Equations Loop Analysis and Node Analysis The Attempt at a Solution The Question states I have to find the equivalent resistance within the circuit. But, since there is a dependent source...
17. ### Need help regarding node analysis and supersposition problems

I've been doing this question for like 2 days and what I find is wrong answer all over again. This is my last resort and I hope my hope is bright. Please if anyone knows how to do it. Include the steps and explanation. I need to understand the concept X_X...
18. ### Node Analysis Help: Solving KCL Equation for I_s

Hi, I have the following circuit [PLAIN]http://img217.imageshack.us/img217/828/upg248.png I need to write a KCL equation to solve for I_s Im really bad at this. But here's what i tried. \frac{v_1}{5} + \frac{v_1 - v_2}{5} + 1 = 0 Im not sure how to write an equation for the...
19. ### Node Analysis for Newbies: Solving Current Source Circuits

Hai, I have this simple circuit [PLAIN]http://img638.imageshack.us/img638/3236/upgp1copy.png And i simply need to solve for the current delivered by the voltage source Vs. How do you write the Kvl equations when you have nonlinear elements like the current divider element in this...
20. ### Node Analysis Question: Solving for Current in a Two-Loop Circuit

Homework Statement This is first time i came across this problem. But let's say u have two loop circuit. in the middle u have a a resistor going down and a it shows let's say 4A current after the resistor. After i make my ground point let's say at bottom of this circuit. Would the equation...
21. ### What Is the Correct Node Analysis for Calculating Voltages at Nodes A and B?

Homework Statement Using mesh analysis work out the currents flow through each of the three meshes. From these current values calculate the voltage of node A and node B with respect to the ground node. XX V has a value of 13. http://www.flickr.com/photos/29385059@N07/2744576925/...
22. ### MATLAB Solving Heat Transfer Problem Node Analysis using Matlab

Can anyone help me solve this problem please ? http://www.hostdump.com/host/out.php/i18940_1.jpg
23. ### Finding Voltages at V1, V2, and V3 using Node Analysis

Homework Statement Find the voltages at V1 V2 & V3 in the attached circuit using node analysis. Homework Equations Node analysis The Attempt at a Solution I came up with a few equations for the variables: V1(.5+1)-12(.5)=5 V2(.333+.25)-V3(.25)=3 V3(.25)-V2(.25)=-5...
24. ### Find Current Drawn from Independent Voltage Source: Node Analysis

Homework Statement (I have attached a picture of the circuit) Using node voltage analysis in the circuit, find the current i drawn from the independent voltage source. Let V=3V, R1=1/2, R2=1/2, R3=1/4, R4=1/2, R5=1/4, I=0.5. Homework Equations I=V/R The Attempt at a Solution I...
25. ### Solve Node Analysis Problem with Ideal Opamp

Hi, I was searching google for answers about my problem and stumbled upon this forum. So I'll post my problem here and hope that some friendly soul can help me :) I need to do a node-analysis of the circuit that I've attached here. The opamp is ideal so Ri=inf and R0=0 and A=inf. I end up with...
26. ### Intro to Elec node analysis help

Hi Guys, I am new to Electrical Engineering and am trying to figure out the voltages for (1) (2) (3) in the link below, assuming that a 5V dc power supply is connected to the terminals on the left. I am new to Elec Engineering and am struggling a bit. I thought to try Node Voltage analysis...