How Can I Correct Errors in My Circuit Mesh Analysis?

In summary, the conversation discusses a homework problem involving solving KVL equations for four meshes and using Ohm's law to find current. The problem requires close attention to signs and assumptions, and it is recommended to write the equations with symbolic values first before substituting numerical values.
  • #1
Toolkit
2
2

Homework Statement



TMA question Mesh analysis.PNG


Homework Equations



I've worked out the KVL's for four meshes, I1, I2,I3, and I4. Would anyone be able to error check this for me?

Also, would I be correct in thinking that I can use ohm's law by dividing V1/Z1 to find the current of the first mesh and likewise with V2/Z3?

The Attempt at a Solution


[/B]
I1 : I1(-2Ω+J5Ω) -J5Ω(I2) = 120∠0°v

I2: -J5Ω(I1) -J4Ω(I2)+J4Ω(I3)+J5Ω(I4)=0

I3: J4Ω(I2) + J8Ω (I3) = 120 ∠90°

I4: J5Ω (-I2) = J5Ω (I4) = 20∠40°

Thanks,

Toolkit

 

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  • #2
Toolkit said:
Also, would I be correct in thinking that I can use ohm's law by dividing V1/Z1 to find the current of the first mesh and likewise with V2/Z3?

That would not be correct. The voltage across Z1 is not just V1. The voltage across Z4 is in series with V1 and those two voltages are then across Z1. The same reasoning applies to the voltage across Z3.

This problem requires close attention to signs of impedances and current directions. You should indicate on the schematic the mesh current directions you have assumed. A common convention is to assume mesh currents are clockwise as shown here. Node designations are also shown which will be handy when doing a nodal solution:

t659iw.jpg


Have you tried solving your equations? I think you have some sign errors. I would write the mesh equations keeping the voltages and impedances in symbolic form (that is, use V2 instead of 120 /_90, use Z1 instead of 2 ohms, Z2 instead of -j5 ohms, etc.). Once you have them written out like that, double check the signs of voltages and currents. When you're sure you have all that right, substitute numerical values for the impedances and voltages.
 

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FAQ: How Can I Correct Errors in My Circuit Mesh Analysis?

What is circuit mesh analysis?

Circuit mesh analysis is a method used to analyze and solve electrical circuits. It involves dividing the circuit into smaller meshes and applying Kirchhoff's voltage law to each mesh to determine the currents flowing through each branch of the circuit.

How is circuit mesh analysis different from other circuit analysis methods?

Circuit mesh analysis is different from other methods, such as nodal analysis, because it focuses on analyzing the voltage drops within the circuit rather than the node voltages. This can be useful for circuits with multiple voltage sources or complex parallel branches.

What are the steps involved in circuit mesh analysis?

The first step is to identify the meshes in the circuit and assign a current variable to each one. Then, Kirchhoff's voltage law is applied to each mesh to create a system of equations. Finally, the equations are solved to determine the currents and voltage drops in the circuit.

What are the advantages of using circuit mesh analysis?

Circuit mesh analysis can be more efficient and accurate for certain types of circuits, such as those with multiple voltage sources or complex parallel branches. It also allows for a systematic approach to solving circuits, making it easier to identify and correct mistakes.

Are there any limitations to using circuit mesh analysis?

Circuit mesh analysis may not be suitable for circuits with non-linear elements or those with a large number of meshes. It also assumes that the circuit is in a steady state, meaning that the currents and voltages are constant. In some cases, other analysis methods may be more appropriate.

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