Solve I(x) in the current using supermesh concept?

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SUMMARY

The discussion focuses on solving for the current I(x) using the supermesh analysis technique in circuit theory. The user initially applied Cramer's rule and an online matrix calculator to derive the currents I2 and I3, ultimately finding I(x) to be 0.08A. However, upon reevaluation, the user corrected their approach by treating the current source correctly, leading to a simplified solution where I3 was recalculated to be 1.75A, resulting in I(x) being -1.75A. The equations used include mesh analysis and the supplementary equation 4A = I3 - I2.

PREREQUISITES
  • Understanding of mesh analysis in circuit theory
  • Familiarity with Cramer's rule for solving linear equations
  • Knowledge of current sources and their representation in circuit equations
  • Basic proficiency in using online matrix calculators
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  • Study advanced mesh analysis techniques in electrical engineering
  • Learn about the application of Cramer's rule in circuit analysis
  • Explore the differences between current sources and voltage sources in circuit design
  • Investigate the use of simulation software for circuit analysis, such as LTspice or Multisim
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Electrical engineering students, circuit designers, and anyone involved in analyzing electrical circuits using mesh analysis techniques.

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Homework Statement


30k6kqt.png


Homework Equations


1111lqw.png

4A = I3 - I2 (supplementary eq.)

Mesh 1:
6(I1)-6(I2)=2A

Mesh 2,3 (supermesh):
6(I2-I1)+6(I2-I4)+12(I3)=0
-6(I1)+12(I2)+12(I3)-6(I4)=0
substitute supp. eq.:
-6(I1)+12(I2)+12(I2+4A)-6(I4)=0
-6(I1)+24(I2)-6(I4)=-48

Mesh 4:
6(I4-I2)=-3A
-6(I2)+6(I4)=-3A


The Attempt at a Solution


|6 -6 0| |I1| = | 2 |
|-6 24 -6| |I2| = |-48|
|0 -6 6| |I4| = | -3|

used cramer's rule (not sure if there was an easier way) and used online matrix calculator http://ncalculators.com/matrix/matrix-determinant-calculator.htm cause i was lazy :(

I2 was all i needed to calculate:
I2 =-1764/432= -4.08A

supp. eq.:
4A+I2=I3
I3= -0.08A

since I(x) is opposite to I3, i got I(x)=0.08A as my answer.
 
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asdf12312 said:

Homework Statement


30k6kqt.png


Homework Equations


1111lqw.png

4A = I3 - I2 (supplementary eq.)

Mesh 1:
6Ω(I1_Amps)-6Ω(I2_Amps)=2Amps

Mesh 2,3 (supermesh):
6(I2-I1)+6(I2-I4)+12(I3)=0
-6(I1)+12(I2)+12(I3)-6(I4)=0
substitute supp. eq.:
-6(I1)+12(I2)+12(I2+4A)-6(I4)=0
-6(I1)+24(I2)-6(I4)=-48

Mesh 4:
6Ω(I4_Amps-I2_Amps)=-3Amps
-6(I2)+6(I4)=-3A


The Attempt at a Solution


|6 -6 0| |I1| = | 2 |
|-6 24 -6| |I2| = |-48|
|0 -6 6| |I4| = | -3|

used cramer's rule (not sure if there was an easier way) and used online matrix calculator http://ncalculators.com/matrix/matrix-determinant-calculator.htm cause i was lazy :(

I2 was all i needed to calculate:
I2 =-1764/432= -4.08A

supp. eq.:
4A+I2=I3
I3= -0.08A

since I(x) is opposite to I3, i got I(x)=0.08A as my answer.

Right away I see a problem in the two equations I've marked in red. I inserted some units and I don't think it's working out very well, is it?

The equation for mesh 1 should be I1_Amps = 2_Amps and similarly for mesh 4.
 
i see my mistake now. i was trying to treat the current source as a voltage source but that's defnitely not right. so the equations are:

I1=2A
I4=-3A

so now this makes everything much simpler. all i need now is the supp. eq. and the eq. for the supermesh:

4A = I3 - I2
-6(I1)+12(I2)+12(I3)-6(I4)=0
-6(2A)+12(I2)+12(I3)-6(-3A)=0
12(I2)+12(I3)=-6V
12(I3-4A)+12(I3)=-6V
24(I3)=42
I3=1.75A
I(x)=-1.75A
 
Last edited:

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