AndrewEE said:
because I feel bad for not knowing ... I apologize ..
I wholeheartedly agree with
@DaveE : they are good questions and of course we are learning (Dave seems to be the expert here, I try to learn as I go along, so I have to look up things that I have little real experience with, e.g. KCL and KVL

).
AndrewEE said:
Everything on the bottom wire = 0 because of the ground, right? So, 3A + 1A - 2A - Iacross 30V?
Not because of the ground but because of KCL plus the fact that there is no current to ground (nothing else is connected to ground). So this way you have the current into the 30 V source -- and thereby the current into A !
AndrewEE said:
Thank you for your reply! Hopefully I can answer you're response. The 30A is actually the 30V supply. When not given resistance, I'm not exactly sure how to handle voltage to translate it to current. I know I = V/R but when there's no R, I don't know what to do.
Now you know: the current comes from elsewhere (the bottom end of the 30 V). And in = out otherwise charge would accumulate ad infinitum.
Re
So the 30 is now 2 Amps and you have given the two others a direction (away from A) so they
both have a minus sign.
Then:
AndrewEE said:
Also, I thought the sum of all voltages across a closed circuit have to = 0. So, wouldn't
V1 + V2 + V3 + V4 + 30V + 10V = 0?
KVL is about the sum of voltages around a closed
loop. I.e. a
single path that returns to the point where it starts. For example from A to A via R1, R2, V2, R3, R4:
V1 ##-## 30 V ##\quad+\quad## V2 ##-## V1 ##\quad+\quad## 10 V ##\quad+\quad## V4 ##-## V3 ##\quad+\quad## 30 V ##-## V4 ##\quad=\quad## 0
Which leaves you with ##\ ## V3 ##-## V2 ##\quad=\quad## 10 V, so I don't think it's very helpful, but there are several more loops ! As Dave says: define a name and a direction for the currents in these loops and thus build a set of equations. If all is well you end up with a set of N equations and N unknowns ... fingers crossed

.
I haven't done the whole exercise (and I'm not even sure I can bring it to a good end) so I depend on you to do the work

-- keep us posted !
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