Hi guys,

I am having trouble figuring out the right equations for the 4 nodes. Can someone tell me what am I doing wrong?

This is what I have so far.

 

I don't see anything wrong with your nodal equation for node 4
I5 = I6 + 28A
(V2 - V4)/4 = (V4 - V3)/2 + 28A

But in your circuit you have 4 node, so to solve this circuit you need only 3 nodal equation. And one of the node you treat as a reference node (GND).

 

OK I will try to solve it that way and let you know if I got the right answers.

 

OK I tried to solve it using the node under v1 as a reference node but I still can't get the right answer. I simulated the circuit with multisim and v1 should be 60V, v2 86, and v3 13. I am still doing something wrong...

 

Hi, you have error in your first equation
I1 is not equal to (40 - V1)/3. You simply forgot about this bottom 1 Ohm resistor. So the correct answer is I1 = (40V - V1)/(3Ω + 1Ω)

http://www.wolframalpha.com/input/?...+C)/4,+(++B+-+C)/4+=+28++C/2,+solve+for+A,B,C

 

OK I tried to solve it using the node under v1 as a reference node but I still can't get the right answer. I simulated the circuit with multisim and v1 should be 60V, v2 86, and v3 13. I am still doing something wrong...

I have a question about v2. It seems to me that v2 is voltage drop across two resistors.

I think you are looking at v2 as being voltage drop across 4 Ohm resistor and I think that is wrong. I think v2 is equal to sum of voltage drop across 4 Ohm and v3.

 

Hi, you have error in your first equation
I1 is not equal to (40 - V1)/3. You simply forgot about this bottom 1 Ohm resistor. So the correct answer is I1 = (40V - V1)/(3Ω + 1Ω)

http://www.wolframalpha.com/input/?...+C)/4,+(++B+-+C)/4+=+28++C/2,+solve+for+A,B,C

I got same answers as Jony.

I used Super Position and Mesh Current. I got:
v1=60 V
v3= -13 V
v2= 73 V

 

Oh OK I got it now, thank you guys!