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Nodevoltage Method, some misconception? 
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#1
May512, 11:49 AM

P: 378

Please check the attachment:
The question is written upon it Sorry bad drawing, the circuit is closed from the left hand side but not from the right hand side. 


#2
May512, 03:28 PM

P: 409

But I don't see any problem. We can choose any node we want as a reference point (GND).



#3
May512, 03:53 PM

P: 378

But the essential node must connect at least 3 appliances!! Here we have only two :/



#4
May512, 05:06 PM

P: 409

Nodevoltage Method, some misconception?
But you can solve the circuit using nodal analysis without any "essential node".
And I still don't understand why you need "essential nodes"? 


#5
May612, 02:05 AM

P: 378

What's nodal analysis? How does it differ from nodevoltage method. Elaborate please.
[I only learnt nodevoltage method :p] If we are talking only nodevoltage method, how in the world did the Doctor consider the node below a reference when it only connects two appliances[see figure]. That's my question. 


#6
May612, 02:25 AM

P: 378

I just checked, and they mean the same. Yet again, this is against the rule.



#7
May612, 03:03 AM

P: 409

Nodal analysis is exactly the same think as nodevoltage method.
And we can choose any node we want as a reference point (GND). See the example We have a four nodes in our circuit. I pick as a reference point (GND) node 4. So node 4 by dedefinition has a potential of 0 V. So we left with three nodes. but we know that voltage at node 1 is equal 9V. So we only has two unknown nodal voltages 2 and 3. Now we apply KCL to the nodes where the unknown voltages appears. For node 2 (I assume that all current flow out from the node) [tex]\frac{V2}{R2} + \frac{V2  V1}{R1} + \frac{V2  V3}{R3} = 0 [/tex] And we notice that V1 = E1 = 10V Now we write KCL for node 3. [tex]\frac{V3  V2}{R3} + \frac{V3  V1}{R4} = 0 [/tex] And now all we have to do is to solve for V2 and V3 http://www.wolframalpha.com/input/?i...+9%29%2F9%3D0 V2 = 3V and V3 = Vth = 6V 


#8
May612, 03:27 AM

P: 378

Lots of thanks Jhony, now I get it..



#9
May612, 03:48 AM

P: 409

We always measure all the voltage respect to this common point (reference point), also known as a "ground" (GND). And we assume that GND have zero voltage.
Look ta this examples 


#10
May612, 11:36 AM

P: 378

Thanks, that's very kind of you.
You really were helpful 


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