Finding potential between two points with opposing voltage sources

[Femme_physics]

Fair enough, thanks :) I'll drop "Norton and friends" and go google some stuff to exercise the basics! Although, I'll do mechanics this month, next month electronics.

 

[I like Serena]

Fair enough, thanks :) I'll drop "Norton and friends" and go google some stuff to exercise the basics! Although, I'll do mechanics this month, next month electronics.

Oh, and I found another good one where you can practice KVL and KCL.
I just know you'll like it.
Here it is:
https://www.physicsforums.com/showpost.php?p=3262139&postcount=3

 

[gneill]

2) With respect to matrices in the solution. We haven't studied matrices in our math-preparation course, and I doubt we will. I'd hate to start extra math just to pick up on an "alternatve path" to solve this stuff. I am interetsted in understanding Norton Equivalents. Are matrices compulsory?

No, matrices are not compulsory. They provide a handy way to organize the calculations, and permit you to bring to bear all the techniques you may have learned in Linear Algebra, but no, they are not compulsory, merely a convenience.

3)

Trying to understand what you did gneill at the attachement.

Plus, I don't see how you could've turned this:

http://img87.imageshack.us/img87/8149/this1b.jpg

To that!:

http://img232.imageshack.us/img232/3737/this2d.jpg


Is it really the same circuit? Because I see different loops I can due in the latter circuit that I can't do in the original. I don't really see where the voltage sources are in here.

It's an equivalent circuit (or model, if you prefer). All the voltage sources in the original circuit have been transformed into current sources, so you won't find any voltage sources in the "new" circuit.

The individual voltage sources and their series resistors get transformed as in the figure in the attachment below, where the Norton current equivalent for one such voltage-resistance is shown. These two source models will behave in exactly the same fashion in any circuit in which they are inserted.

For the circuit images that you've provided, you should be able to identify the voltage/resistor and current/resistor pairs that correspond in the two diagrams.

 

[Ouabache]

@gneill: have you considered putting your explanation of Norton on the wikipedia page?
I think that would be a valuable addition. :)

@stevenb: have you considered putting the content of your guidebook of Kirchhoff's laws on the wikipedia page?
I think that would be a valuable addition. :)

The articles as they are now could use some improvement.

Although Wiki does have many useful entries, we are working on our own https://www.physicsforums.com/library.php" of core
concepts on PF.. I don't see many EE topics covered yet. These two certainly would fit.
The Kirchoff notes that stevenb touched on, are typically taught in a 1st yr Linear
Circuits course, but I have not seen them summarized well on ref websites.
You may also compare entries on http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html" . For those who may not
have used hyperphysics before, they have excellent illustrative material.

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/norton.html#c1" (be sure to scroll down their pages).

 

[flyingpig]

edit: made a mistake

 

[Antiphon]

There's another easy solution; superposition.

Solve the problem with two of the generators set to zero. Do this three times, once for each non-zero generator and add the voltages.

 

[flyingpig]

OKay honestly there is much much easier way to do this. Use Mesh's method and you only have to do with 2 unknowns. If you are scared with simutaneous equations, use a matrix. ALso nice hair dude.

Also just for my own learning sake, do you just add the total voltage drop in the middle branch?

Say 9V + voltage drop across resistor R₂?

It shuold be a negative voltage drop right?