Im stuck on my electric curcuit homework could u guys help me

ericgibbs

Joined Jan 29, 2010
13,665
hi,
OK,
First check out page 2-2 of this PDF, [Fig 2-4 ] look over the equations for that IA configuration.

Post your calculations

Ask if you have a problem.
E
 

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Thread Starter

xElvis

Joined Apr 18, 2021
6
first my writing skills is very bad :D sorry for that and im just trying to solve another question can i show u for check?
here its and again sorry for ur eye healt :D now im trying to find c part could u help me :/
 

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Yaakov

Joined Jan 27, 2019
3,522
I took a quick look at your written work but I have to go do something for about an hour and had some trouble reading it. I fixed it up a bit so if someone else has the chance to help it might be easier. I’ll try to take a look when I get back.

7D0D143C-CA31-4578-8746-65B1C01B52CE.jpeg
 
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Yaakov

Joined Jan 27, 2019
3,522
its better thanks for that
I don’t want to leave you hanging. The maths are not my strong suit and so I am having a very hard time with your solution. It’s extremely hard for me to follow your notes. There are people here who are much better in this area than I am and I am hoping someone will step up, or Eric when he Is available.
 

Thread Starter

xElvis

Joined Apr 18, 2021
6
I don’t want to leave you hanging. The maths are not my strong suit and so I am having a very hard time with your solution. It’s extremely hard for me to follow your notes. There are people here who are much better in this area than I am and I am hoping someone will step up, or Eric when he Is available.
I think thats not require master math skill just need to know where to use formula thats the problem :D thanks for ur interest ım very appreciete and when eric is online he probably help lets see
 

RBR1317

Joined Nov 13, 2010
664
just need to know where to use formula thats the problem
One does not need a formula to write node equations; what you need is a procedure. There are several possibilities for expressing the notion that the sum of currents at a node must equal zero, but I will describe the one that is easy (for me) to remember and any errors are easy to find.

First: color-code the nodes and label the node voltages.
Second: write the node equations for each node. The sum of currents at each node equals zero.

Current at a node has the following form: [(Node Voltage) - (Adjacent Node Voltage)]/(Resistance to adjacent node)
Note that each term of the node equation begins with the voltage of that node. For instance, the current through R1 has the form (V2-V1)/R1 in the node equation for V2; but has the form (V1-V2)/R1 in the node equation for V1.
For defined current sources, current leaving the node is considered positive in the node equation.

For a circuit with dependent sources, express the dependency in terms of the node voltages.

By always using the same exact procedure I can generally just look at the color-coded circuit and type the node equations directly into Maple, then let the Maple solver crank the algebra and do the Bode plots, etc.
 

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You have some sign errors. The current from the 2A source is entering node 1 and leaving node 2; it can't have the same sign in both equations. Also the sign of the 4A current should be the same as the sign of the 2A current in the equation for node 2 because both currents are leaving node 2.
 
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