# mesh analysis PROBLEM

Discussion in 'General Electronics Discussion' started by djengala, Feb 4, 2016.

1. ### djengala

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Feb 4, 2016
hi all im new in electronics and las week i had an exam and a question on the exam was how many meshes are in this circuit http://puu.sh/mUbFA/98ed6b8ad1.png really basic meshes no super meshes or somthinng like that

5,177
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Dec 18, 2013
What was his answer, you didn't say.

3. ### djengala

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Feb 4, 2016
his answer was 13 mesh but i think its 4

5,177
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Dec 18, 2013
I would have said 4 also. But there must be a reason he said 13?

5. ### djengala

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Feb 4, 2016
HERE are the 13 meshes he took

5,177
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Dec 18, 2013
Well yeah but to work it out I dont think you need all 13. I know a guy that will know all this @Ratch, care to comment?

7. ### Ratch

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Mar 10, 2013
Depending on the definition of a mesh, I would think that if you can write a KVL equation on it, it is a mesh. For instance, using the above numbering, and selecting loops #9, #5, and #7, one could solve for all the voltages and currents. That is because those three loops cover all the resistors and voltage source. There are other combinations that also cover all the circuit elements.

Ratch

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8. ### djengala

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Feb 4, 2016
isnt it a single loop ?

9. ### Ratch

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Mar 10, 2013
Isn't what a single loop?

Ratch

10. ### Harald KappModeratorModerator

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Nov 17, 2011
Of course you can draw 13 meshes as shown in post #5. This is what the exam asked for, therefore the teacher's answer is correct.
This kind of "test" is a common entertainment.

It is, however, not necessary to identify these 13 meshes and set up the equations for them to solve the circuit, see post #7 by Ratch. This is where you have gotten confused during the exam. In any test, not specifically an electronics exam, it is essential to carefully read and understand the task before answering.

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11. ### djengala

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Feb 4, 2016
well this kinda sucks because if there is no point in identifying the other meshes then why bother

Last edited: Feb 6, 2016
12. ### dorke

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Jun 20, 2015
Well,

The definition of a Mesh(in planar circuits) is:
A loop which does not enclose any other loops.
That number here is indeed 13 as shown.

A different question is what is the minimal number of mesh equations needed to "solve" this circuit.
That number here is 1!
Hint:
That circuit can be easily "degraded" to a single mesh (#1) by parallel and serial equivalents of most resistors in it...

Last edited: Feb 7, 2016
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13. ### djengala

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Feb 4, 2016
thank you for the explanation