Confirmation with exercises on thévenin (part two)

jorgemotalmeida

Joined Oct 23, 2007
23
Hi

This one... I've tried to use mesh analysis... but it seems more tricky... please tell me what I'm doing wrong in this exercise.

I attached 3 files. See first the exercise1_1part.jpg, then exercise1_2part.jpg, and finally the file named as quizz22.jpg

Please see the quizz22 and tell me how comes the value V Thev = (60) (60) / 80 ... in the other 2 files, the doubts are identified.

Thanks.

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jorgemotalmeida

Joined Oct 23, 2007
23
I forgot to put the first file. Here goes...

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jorgemotalmeida

Joined Oct 23, 2007
23
I realized why I mistaked on mesh analysis... because really i2-i1= 1,5 A and not i2=1,5 A. we have a super mesh! I will make it again.

Please see now only the other doubts. Thanks.

edit:

Is it right? >>>

Mesh 1 and Mesh 2:

60 i2 + 20 i2 + 30 (i2 - i3) + 10 (i1 - i3) + 40 i1 = 0

Mesh 3:
-30 + 10 (i3 - i1) + 30 (i3 - i2) = 0

Mesh 3 + Mesh 2 : i2 - i1 = 0

Then it appears like this:

50 i1 + 110 i2 - 40 i3 = 0
-10 i1 - 30 i2 + 40 i3 = 30
-i1 + i2 = 1

resolving the system give us .... i1 = -0.417 A and i2 = 0.5833 A...

If our V(A) is V = R I == V = (60+20) * i2 == V = 80 * 0.5833 and it gives 46,64 V....

NOT so precise as nodal analysis.. (it gave 45 V)

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