Engineering Confusing circuit analysis question

[anon6912]

Hi

I have the following situation:
(Please see attached pic)

I want to know if equation (4) i have written is correct.

What is confusing me is that, I remember being told in circuit analysis that each energy storage element should have its own state variable.

But in this situation when I apply KCL at node 1 and using that relationship I am seemingly able to write iL in terms of the other two variables.

I can apply KCL there can't I?
and if I can apply KCL at that node then I can get il = ig + is?
then I can substitute this result in eq1 to get eq4?

But this seems to violate what I have learned in class of each energy storage element needing its own state variable.

Any help is much appreciated.

Thank you

 

[Delta2]

if we consider the current through each energy storing element as its state variable then I don't see what it is that bothers you.

Each element having its own state variable, doesn't necessarily mean that the state variables of various elements are independent from each other, the elements interact with each other with various ways when they are connected in a circuit in various ways, so their states become dependent from each other, so the state variables become dependent from each other as well.

 

[anon6912]

Thank you. That clarified my doubt