I can only find 3 of the 4 equations to satisfy 4 unknowns. What am I missing?


Joined Mar 31, 2012
It would help if you used your colors consistently. In your second diagram you have two yellow nodes and the pink node from the first diagram has disappeared.

Also, in your first diagram your dependent current source is controlled by "Vs", but there is no "Vs" identified on the diagram.

Then, in your second diagram, it is controlled by "Vb", so why the switch?

If you are counting "Vb" in the second diagram as an unknown, the what is the relationship between Vb, I1, and your R123 equivalent resistor?

EDIT: Fixed typo pointed out below by The Electrician. Thanks!
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The Electrician

Joined Oct 9, 2007
All you need is the two mesh currents you've labeled A and B (which are the same as i1 and i2). Two equations suffice to find those two Everything else falls out from them.


Joined Mar 31, 2012
What you've done is almost a solution by branch currents. Do you know the supermesh technique?
My impression is that they are just covering KCL/KCL and applying them to branches and loops. My guess is that they'll be hitting mesh and nodal analysis pretty soon, depending on when they cover superposition.