Finding the Voltage across a Resistor using the Node Voltage Method

In summary, the conversation discusses finding the voltage across resistor 3 in a given circuit, using Kirchhoff's Current Laws and Cramer's rule. The person asking for verification on their KCL equations and suggests checking the signs. It is recommended to write KCL equation for the ground node and to use the method of replacing voltage sources with current sources.
  • #1
rugerts
153
11

Homework Statement


For the given circuit (see below), find the voltage across resistor 3.

Homework Equations


n-1 Kirchhoff's Current Laws for n nodes.

The Attempt at a Solution


IMG-1912.JPG
IMG-1913.JPG


Can anyone verify whether my KCL equations are correct? The mixture of source voltages with node voltages may have stumped me as far as finding a relevant expression for current across for example resistor 4.
My answer for V1, which is the same as the voltage across resistor 3, comes out to 134.59 V and the answer appears to be 84.54 V.
I have tried using Cramer's rule.

Here are imgur links incase the above images are too blurry:
https://imgur.com/KKL49X7
https://imgur.com/N79tdYo
 

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  • #2
rugerts said:

Homework Statement


For the given circuit (see below), find the voltage across resistor 3.

Homework Equations


n-1 Kirchhoff's Current Laws for n nodes.

The Attempt at a Solution


View attachment 239069 View attachment 239070

Can anyone verify whether my KCL equations are correct? The mixture of source voltages with node voltages may have stumped me as far as finding a relevant expression for current across for example resistor 4.
My answer for V1, which is the same as the voltage across resistor 3, comes out to 134.59 V and the answer appears to be 84.54 V.
I have tried using Cramer's rule.

Here are imgur links incase the above images are too blurry:
https://imgur.com/KKL49X7
https://imgur.com/N79tdYo

Check the signs in your equations. Remember, the current flows from higher potential to lower one.
Also, it would be easier to write KCL equation for the nod at the ground instead of node 2.
 
  • #3
The most efficient way would be to use the method of replacing the voltage sources with current sources and vice verse.
 

What is the Node Voltage Method?

The Node Voltage Method is a technique used to find the voltage across a resistor in a circuit by analyzing the currents and voltages at different nodes or junctions in the circuit. It is based on Kirchhoff's Current Law and Ohm's Law.

When is the Node Voltage Method used?

The Node Voltage Method is used when there are multiple resistors connected in series and/or parallel in a circuit. It is especially useful in more complex circuits where the traditional methods of finding voltage may be difficult.

What are the steps to using the Node Voltage Method?

The steps to using the Node Voltage Method are:

  1. Identify all the nodes in the circuit.
  2. Select one node as the reference node and assign it a voltage of 0.
  3. Write down Kirchhoff's Current Law equations for each node (except the reference node) by considering the incoming and outgoing currents.
  4. Use Ohm's Law to substitute any known voltages or resistances in the equations.
  5. Solve the resulting system of equations to find the voltages at each node.
  6. Use the voltage at the desired node to find the voltage across the resistor in question.

What are the advantages of using the Node Voltage Method?

The Node Voltage Method offers several advantages, including:

  • It can be used for circuits with multiple resistors connected in series and/or parallel.
  • It is a systematic and organized approach to solving complex circuits.
  • It can be easily applied to circuits with dependent sources.
  • It can be used to find the voltage at any node in the circuit, not just the voltage across a specific resistor.

Are there any limitations to using the Node Voltage Method?

The Node Voltage Method may not be the most efficient method for simple circuits with only a few resistors. It also requires a good understanding of Kirchhoff's Current Law and Ohm's Law. Additionally, it may become more complicated to use if there are non-linear elements in the circuit, such as diodes or transistors.

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