# nodal analysis question

#### WBahn

Joined Mar 31, 2012
26,398
Thank you for your detailed observations.
Apologies for my sloppiness, the colours seemed a good call but now you mention it, it'll prove troublesome in the future
Live and learn. I've tried a number of tricks and techniques over the years and most of them turned out to be bad (or at least ineffective) ideas for one reason or another. But some of them have worked out well and I continue to use them to this day. Keep experimenting.

As for the sloppiness, that's not unusual. Deal with it now and you can save yourself LOTS of grief down the road. Otherwise, you will deal with it after you go through lots of grief down the road. Either way, it's almost certain that you WILL deal with it.

#### chrischivers1

Joined Mar 23, 2015
14
The final line in red, is where I am trying to bring in the R4 & R5 since they are essentially in series, I didn't know how to bring them into an equation.. Past examples ive done have had a second voltage etc so you'd add a V3 and do it that way.

#### WBahn

Joined Mar 31, 2012
26,398
The final line in red, is where I am trying to bring in the R4 & R5 since they are essentially in series, I didn't know how to bring them into an equation.. Past examples ive done have had a second voltage etc so you'd add a V3 and do it that way.
I'm not following. The work in red has to do with Node V1 and has nothing to do with R4 or R5 since those are on the other side of V2.

R4 and R5 aren't essentially in series, they ARE in series.

Your first equation in black, namely Ia + Ib + Ic = 0, is just fine.

Your second equation in black is fine, provided you add in the proper units and get rid of the "Ia = " from the left side of it.

Going from your second equation to what should be the third equation has nothing to so with EE -- it's pure algebra. You want to manipulate that until you have it in the form

k1·V1 + k2·V2 = Vo

In this case, Vo=0.