Engineering Circuit Analysis - Source Transformation

AI Thread Summary
The discussion revolves around using source transformation to find the voltage Vx in a circuit analysis problem. The user applied Kirchhoff's Voltage Law (KVL) and performed calculations, initially arriving at Vx = -6.11 V. However, there was confusion regarding the polarity of Vx, with a clarification that Vx should actually be considered as 5I, leading to the correct value of Vx being 6.11 V. The importance of following conventions for current and voltage sources during transformations was emphasized. Ultimately, the calculations were verified, confirming the correct approach to source transformation.
timeforplanb
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Homework Statement


Find Vx using source transformation
attachment.php?attachmentid=41205&stc=1&d=1322126072.jpg


Homework Equations


V=IR
KVL

The Attempt at a Solution


After doing source transformation on the three pairs of current sources and resistors...
attachment.php?attachmentid=41207&stc=1&d=1322126953.jpg


KVL:
-6+2I-Vx+4I-3+3I+5I-2=0
14I-Vx-11=0
but Vx=5I (is it? I'm not so sure about this)
14I-5I-11=0
1I=11
I=1.222 A

Vx=-5I=-5(1.222)
Vx=-6.11 V

Did I do the source transformation right? Also, I'm confused with the value of Vx. Is it -5I or just 5I? Because in our class, our convention is that when a current source is transformed into a voltage source, the part where the arrow head in the current source becomes the positive terminal for the voltage source. But since we're only dealing with a resistor here, I just followed our convention for the KVL (the voltage across 5 ohms is positive since the mesh current enters the positive terminal)
 

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Everything looks fine except for your last two lines! Vx is in fact 5I, since its specified polarity indicates that it's a drop in the same direction as your current. So Vx = 6.11 V.
 
Last edited:
thank you very much for the verification sir!
 

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