# Help with superposition questions

#### rawchicken

Joined Nov 27, 2016
2
Hello,

In the circuits in the following images I'm struggling to understand how to get the values for both energy sources. I can do it for the 10V sources in each but in both circuits I can't figure out how to get the values asked for in the question from the other energy sources. Any help is appreciated!

Question 1: Question 2: Thanks

#### timekeeper

Joined Oct 24, 2007
8
The superposition theorem as the name implies, states that every source contributes to the circuit as it was the only one present. To use the superposition theorem, you have to do a circuit analysis with only one source at the time and then add the results for the node you are interested in. In the first example you have to do 2 analysis, each for every power source. For V1 analysis you have to short (replace with a wire) V2 and calculate voltage at node A with respect to node 0. After that, short V1 and do the same analysis for V2. Now you simply have to add the two voltages values at point A and you get your result.
When you are dealing with current sources as in your second question you don't short them but you OPEN them. So, you have to open I2 when analysing for V1 and short V1 when analysing for I2.

#### shteii01

Joined Feb 19, 2010
4,644
Ok. I got to ask. I have paid hundreds of dollars for textbooks back when I was getting my BSEE. timekeeper is telling this dude exactly what any textbook would have told him. And the textbook would have an example or two that the student can work through and would know what to do with homework problem.
Do they still make students buy textbooks?
Or is it all power point slides and students don't have a clue what to do since those slides don't actually have any background information?
Or is the dude just lazy?

(being a lazy dude myself, I vote for #3)

• DGElder

#### WBahn

Joined Mar 31, 2012
26,280
Hello,

In the circuits in the following images I'm struggling to understand how to get the values for both energy sources. I can do it for the 10V sources in each but in both circuits I can't figure out how to get the values asked for in the question from the other energy sources. Any help is appreciated!
Please show your best attempt to work your homework problems. That will give us the chance to see what you are doing and where you are going astray to help you get back on track.

#### MrAl

Joined Jun 17, 2014
7,849
Hello,

In the circuits in the following images I'm struggling to understand how to get the values for both energy sources. I can do it for the 10V sources in each but in both circuits I can't figure out how to get the values asked for in the question from the other energy sources. Any help is appreciated!

Question 1: Question 2: Thanks
Hi,

Do you at least know that you have to change the circuit a little to get the answer using superposition?
Do you know how to manipulate the sources and then sum the results?