I really need to learn how to do Nodal Analysis by Inspection before Wednesday

[VinnyCee]

I really need to learn how to do "Nodal Analysis by Inspection" before Wednesday!

My Prof. told us (very quickly) about some easy method for circuit analysis called "Inspection". Can someone explain, in detail, how this is done? If you want a circuit to demonstrate on, just check my old posts and copy a suitable circuit from there to here.

Thanks!

 

[VinnyCee]

How about this circuit? It has already been solved by using traditional nodal analysis https://www.physicsforums.com/showthread.php?t=152718".

http://img248.imageshack.us/img248/7325/chapter3problem301dy.jpg

 

[VinnyCee]

Anyone here know how to explain the "by Inspection" part of Nodal Analysis?

 

[karlthesmith]

Really late on this one but helpful for those who will be stuck.

This Place has the best explanation that I have found for node analysis or mesh analysis by inspection.

http://commons.bcit.ca/math/examples/elex/linear_algebra/backgd5a.html"

 

[Yaz Li]

Though it is late, but no harm in commenting.
If you inspect that circuit, you will see that the voltage difference between terminals of the 40 Ohm is 120 V. The reason is that the positive terminal of the voltage source is connected to the other side of the 40 ohm resistor. Therefore, Io can be easily found; it is the current of the 40Ohm and we know the voltage drop of that. Thus, Io=120V/40 Ohm=3A.
For Vo, it is the voltage drop of a short circuit. Therefore, Vo=0V.
I solved some tricky problems http://circuits.solved-problems.com/basic-concepts/problem-1-13-voltage-current-source/" .