How Do You Solve This Complex Mutual Inductance Problem?

AI Thread Summary
The discussion centers on solving a complex mutual inductance problem, where the user initially derived equations for currents I1 and I2 but obtained results that did not match the provided answers. A participant pointed out a sign error in the user's equations, suggesting corrections to the mutual inductance treatment. After reviewing previous examples, the user acknowledged the mistake and successfully identified the error in their calculations. The conversation highlights the importance of careful equation formulation in mutual inductance problems. Ultimately, the user resolved their confusion and corrected their approach.
p75213
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Homework Statement


See attached.


Homework Equations





The Attempt at a Solution


(5+j8)I1-j6I2-j3I2-j3I1*2=magnitude(12) degrees (60)
(5+j2)I1-j9I2=magnitude(12) degrees (60)

j2I2-j6I1-j3I1=0
-j9I1+j2I2=0

I put these equations into mathematics software and get the answers:
I1=magnitude (0.3091) angle (142.60) degrees
I2=magnitude (1.3909) angle (142.60) degrees.

These are not the answers provided. Can somebody show me where the error is?
 

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p75213 said:

Homework Statement


See attached.


Homework Equations





The Attempt at a Solution


(5+j8)I1-j6I2-j3I2-j3I1*2=magnitude(12) degrees (60)
(5+j2)I1-j9I2=magnitude(12) degrees (60)

j2I2-j6I1-j3I1=0
-j9I1+j2I2=0

I put these equations into mathematics software and get the answers:
I1=magnitude (0.3091) angle (142.60) degrees
I2=magnitude (1.3909) angle (142.60) degrees.

These are not the answers provided. Can somebody show me where the error is?

Can you show how you derived your equation? I'm concerned about how you treated the mutual inductance. Perhaps assign variable names to the component values for easy tracking in the equations.
 
p75213 said:
[

The Attempt at a Solution


(5+j8)I1-j6I2-j3I2-j3I1*2=magnitude(12) degrees (60)
(5+j2)I1-j9I2=magnitude(12) degrees (60)

j2I2-j6I1-j3I1=0
-j9I1+j2I2=0

You have a sign error. The equations should be:

(5+j8)I1-j6I2+j3I2-j3I1*2=magnitude(12) degrees (60)
(5+j2)I1-j3I2=magnitude(12) degrees (60)

j2I2-j6I1+j3I1=0
-j3I1+j2I2=0
 
The Electrician said:
You have a sign error. The equations should be:

(5+j8)I1-j6I2+j3I2-j3I1*2=magnitude(12) degrees (60)
(5+j2)I1-j3I2=magnitude(12) degrees (60)

j2I2-j6I1+j3I1=0
-j3I1+j2I2=0

Thanks for that. I had to go over some of the previous examples in the book. However I figured out what I was doing incorrectly.
 
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