Analyze this circuit with 2 sources and 4 resistors

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SUMMARY

The discussion focuses on analyzing a circuit with two sources and four resistors, specifically addressing the current flow and the implications of a dependent voltage source labeled "5i." Participants emphasize the necessity of applying Kirchhoff's Current Law (KCL) and setting up a system of equations to solve for the voltages at the nodes (v1, v2, v3) using nodal analysis. The circuit's configuration includes a 2Ω resistor and a 6Ω resistor, with the latter being deemed irrelevant to the overall analysis due to its placement across voltage sources.

PREREQUISITES
  • Understanding of Kirchhoff's Current Law (KCL)
  • Familiarity with nodal analysis techniques
  • Knowledge of dependent and independent voltage sources
  • Basic circuit analysis skills, including Ohm's Law
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  • Study the concept of supernodes in circuit analysis
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  • #31
mkamalzayed said:
Depending on your assumptions
Node v2 does not receive any current
How do I apply the KCL law?
v2 receives i2, i4, i5.
 
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  • #33
mkamalzayed said:
Where????
These currents flows out of v2
View attachment 353471
Look at the diagram in post #15. i2, i4 and i5 are shown.
 
  • #34
i2,i4,i5 flows from v2
There are not currents entering the node v2
 
  • #35
mkamalzayed said:
i2,i4,i5 flows from v2
There are not currents entering the node v2
You are forgetting what BvU said in post #15: "No worries about the directions of the currents: the correct sign will come out in the analysis."

The arrows on the diagram may not be showing the direction of physical current flow. What if i2 has a negative value?
 
  • #36
Proceed like this. First note that the 6 ohm resistor is connected across voltage sources so it has no effect on the values of v1, v2 and v3; remove it--that means i6=0.

Treating v1, v2 and v3 as a supernode means that you don't write 3 KCL equations for each of v1, v2 and v3. Instead you write one KCL equation for the supernode (the supernode being the combination of v1, v2 and v3). That equation expresses the fact that the sum of the currents entering or leaving the supernode sum to zero.

If i6=0, then i=i4 and i3=i5 so the 3 currents i, i2 and i3 are the only currents entering or leaving the supernode. So we have i+i2+i3=0. Can you express that equation using v1,v2,v3 and the values of the 3 resistors?

To finish you'll need two constraint eqations; I'll help you with those.
 
  • #37
mkamalzayed said:
How ?? "5i" is a current not a voltage
BvU said:
The diamond
1730723722591.png
represents a dependent voltage source of 5i Volts, where i is the current through the 2Ω resistor (
1730723903277.png
in the diagram).


You have chosen not to answer any of the questions asked in #14, so why should I bother to answer
mkamalzayed said:
Depending on your assumptions
Node v2 does not receive any current
How do I apply the KCL law?
Before diving into supernodes, you should first come to understand the diagram and why KCL says ##\ \ i_2+i_4+i_5=0\ \ ## (or ##-i_2-i_4-i_5=0##, which is equivalent).



##\ ##
 
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  • #38
The OP is on a 10-day vacation from PF for several issues, so I'll go ahead and close this thread for now. It may be reopened after the OP is back if they send me a PM and show me what they understand about this circuit analysis. Thank you to all who have been patiently trying to help this user in this thread.
 

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