Engineering Superposition calculation for a circuit

AI Thread Summary
The discussion revolves around a superposition calculation for a circuit, where the user expresses frustration over discrepancies between their results and expected values. They detail their approach, including impedance calculations with complex numbers, but receive feedback indicating errors in their calculations, particularly in the imaginary components. The user acknowledges these mistakes and seeks clarification on how to correct them, specifically regarding the handling of terms in their equations. The conversation highlights the importance of careful manipulation of complex fractions in circuit analysis. Overall, the user is committed to improving their understanding and accuracy in solving the problem.
billyray
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Homework Statement


I have tried to answer the superposition question in the included file. I have gone through the workings as the same as in my john bird electrical book. I believe I have done nothing wrong in my approach and should be getting the same answer as my thevenins answer. the current through the load is completely different though

Homework Equations


total impedance when v2 removed = j4 in series with parallel j6 and 35 + j 35 .71
v1 removed total impedance j6 in series with parallel j4 and 35 + j35.71
then volts over resistances to find I then use the currents to find load current adding i2 and i5.
i1 x j6/j6 + 35 + j 35.71 = I2
i4 x j4/j4 + 35 + j35.71 = 1 5

i5 + i2 = I load

The Attempt at a Solution


it is included in file
I have added my attemp
 

Attachments

Last edited by a moderator:
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Hi billyray,

Welcome to Physics Forums!

I've just taken a look at your work for the first part where you've suppressed the V2 source, and I find that I don't agree with your net impedance value. In particular, the imaginary component looks incorrect to me. I think things started to go off the rails when you were dealing with the numerator during the normalization of the complex fraction. This is the bit I'm referring to:

upload_2017-11-21_9-42-0.png
 

Attachments

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    upload_2017-11-21_9-42-0.png
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hi Gniell
Thank you so much for listening. I am trying very hard and small mistakes and lack of confidence is frustrating me. I have studied a lot for this and thought I could do it. I have changed the numerator as I see I did not add j4 do you think it is more wrong than this?. I have attached my correction.
 

Attachments

I then multiplied by the conjugate of the denominator that was 35- j35.71
 
You're good until the last two lines. You can't add the j4 to the numerator at that point: it's a separate term with a different denominator.
 
Thanks gneill
i will redo
 
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