R
R.Spinks
 Jan 1, 1970
 0
I seem to be unable to properly calculate the proper voltage for what I've
called Node B. Would someone mind helping me discover where I've turned a
wrong corner here. Schematic below (top right corner and top of 3Vx
source  ie. I drew an ideal wire  it's the same node : Node B):
2i
..
dependent
current  Node B
 source +,
   ,´ 
 '' ´ 
 ,´ 
 5 ohm 2 ohm ,´ 
 ___ ___ ,´ 
Node A______,´ 
 ,´  
 Vx + ,´  
 ,´  
 ,´  
 ,´  
.. ´ i  
 Indep.  /+\ .. ..
10 A  current ( ) 3Vx    5 ohm   1 ohm
 source  \/ \/   
   '' ''
''   
   
   
   
   
   
   

 

GND
(created by AACircuit v1.28.4 beta 13/12/04 www.techchat.de)
Here's the math I did:
5ohm  1 ohm = 5/6 ohm
5ohm in series 2 ohm = 7 ohm
i=Vb / 5 ohm
Vb=3Vx
KCL @ A:
10+((VbVa)/7)  2i =0
10+(Vb/7)(Va/7)2Vb/5=0
Vb(1/7  2/5)  1/7 * Va = 10
0.25714Vb 0.14285Va = 10 (I simulated the problem and this part is
correct)
KCL @ B:
2i  ((VbVa)/7  (6/5)*Vb = 0
(2/5)Vb  (Vb/7) + (Va/7)  (6/5)*Vb =0
(2/5  1/7  6/5)Vb = 1/7 Va
Va = 6.6Vb (this is incorrect based on my simulation)
I expect the answer to be voltage a node b to be 30v and at node a to be 16
volts. What have I done incorrectly? Thanks.
called Node B. Would someone mind helping me discover where I've turned a
wrong corner here. Schematic below (top right corner and top of 3Vx
source  ie. I drew an ideal wire  it's the same node : Node B):
2i
..
dependent
current  Node B
 source +,
   ,´ 
 '' ´ 
 ,´ 
 5 ohm 2 ohm ,´ 
 ___ ___ ,´ 
Node A______,´ 
 ,´  
 Vx + ,´  
 ,´  
 ,´  
 ,´  
.. ´ i  
 Indep.  /+\ .. ..
10 A  current ( ) 3Vx    5 ohm   1 ohm
 source  \/ \/   
   '' ''
''   
   
   
   
   
   
   

 

GND
(created by AACircuit v1.28.4 beta 13/12/04 www.techchat.de)
Here's the math I did:
5ohm  1 ohm = 5/6 ohm
5ohm in series 2 ohm = 7 ohm
i=Vb / 5 ohm
Vb=3Vx
KCL @ A:
10+((VbVa)/7)  2i =0
10+(Vb/7)(Va/7)2Vb/5=0
Vb(1/7  2/5)  1/7 * Va = 10
0.25714Vb 0.14285Va = 10 (I simulated the problem and this part is
correct)
KCL @ B:
2i  ((VbVa)/7  (6/5)*Vb = 0
(2/5)Vb  (Vb/7) + (Va/7)  (6/5)*Vb =0
(2/5  1/7  6/5)Vb = 1/7 Va
Va = 6.6Vb (this is incorrect based on my simulation)
I expect the answer to be voltage a node b to be 30v and at node a to be 16
volts. What have I done incorrectly? Thanks.