# graph theory - circuits

Joined May 9, 2017
1
Hello everyone.

I am having a problem graphing a circuit as I'm quite unfamiliar with this field.

This is a first example which I think I got right; I find all the nodes and then connect the individual branches. Where I do encounter a problem is with some examples which are not as obvious as this one.

I see that there are ultimately two nodes; but the "excess" wires make it confusing (the one connecting the nodes between R1,R2 and R3,R1 as well as the one above) to graph. I was first thinking what happens if I would just ignore the wire (a short circuit) and then do some serial connecting of resistors - R1-R2 and then parallel it with R3 but I don't even know if I'm supposed to do that as the assignment is just to graph it. I guess I'm asking an embarrassing question but please bare with me.

#### shteii01

Joined Feb 19, 2010
4,644
Technically the wire is a resistor whose value is zero. So if the wires give you trouble, you can replace them with the "boxes" like all the other resistors, just provide the note to the instructor informing them about your approach.

May I ask what is the point of the exercise?

#### MrAl

Joined Jun 17, 2014
7,849
Hello,

Looks like maybe he is after a signal flow graph. For example a voltage divider with two equal resistors would look like this:
Code:
o----->-----o
1/2
He could be up to something else too i guess.

#### WBahn

Joined Mar 31, 2012
26,295
R1 and R2 aren't in series. In order to be in series, whatever current flows in one component must the same identical current that flows in the other. You can't just ignore a wire -- you've changed the circuit by doing so.