# Computing UAB0 for a thevenin problem

Discussion in 'Homework Help' started by para, Jun 19, 2009.

1. ### para Thread Starter New Member

Jun 19, 2009
3
0
Greetings to all,
I am new to this forum I have a circuits exam and I need to learn how to solve some problems. This one in particular that I want to ask about I am supposed to solve with Thevenin. I am supposed to compute the current intensity(I) through resister R5 - I5(I did not draw it it is supposed to be on the right of A-B it is the only thing that is on the right of A-B but that is not important).
Now, in order to compute this current with Thevenin I am supposed to compute UAB0 the open circuit voltage difference between A and B which as I understand it is UAB0 = VB - VA. Please correct me if this is wrong

I want to know how I can compute this(UAB0)? Can anyone tell me please.

Ah ... the circles with arrows inside them are voltage sources and the rectangles are resisters this is how they denote them in my country.

2. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
782
Does the problem only have symbolic values (R1, R2 etc) or were you given actual values as well?

3. ### hgmjr Moderator

Jan 28, 2005
9,030
214
It would be best if you would post your effort at finding a solution on your own rather than have us blurt out the answer.

Were you required to apply a particular circuit analysis method?

hgmjr

4. ### para Thread Starter New Member

Jun 19, 2009
3
0
there were some symbolic values also I'll post them when I get home(@work now)

E2 = 40
E4 = 80
R1 = 5
R2=R3=R4 = 10
R5=20

Last edited: Jun 19, 2009
5. ### para Thread Starter New Member

Jun 19, 2009
3
0
well I tryed loop current method and node potential method but that got me nowhere and as I understood I can't use a voltage divider because there are voltage sources in the circuit ...
I just want to compute UAB0 somehow if I were to know it I could find the intensity through I5 with Thevenin's theorem
It makes no difference how I compute it.
Please if anyone knows ... I really have worked hard but I'm stuck ... honest

6. ### hgmjr Moderator

Jan 28, 2005
9,030
214
One of the easiest analysis methods to use in such a problem is the Superposition Theorem.

The goal is to use the Superposition Theorem to calculate the contribution of each of the individual voltage sources to the voltage across the terminals of interest. Once you have the contribution of each the individual voltages then you will add them algebraically together to get the net voltage across the terminals of interest. This net voltage will be the Thevenin Voltage across the terminals of interest.

hgmjr