# can you help me please ?

Discussion in 'Homework Help' started by KFUPM University, Apr 28, 2011.

1. ### KFUPM University Thread Starter New Member

Apr 28, 2011
9
0
hi guys , I am having difficulty in solving this circuit by transformation

can you show me the steps and how to find Vx(voltage)

File size:
142.9 KB
Views:
26
2. ### jegues Well-Known Member

Sep 13, 2010
735
43
Start off by transforming the two voltage sources and series resistances on the left hand side of the circuit into current sources with parallel resistances.

After doing so you should be able to make a parallel combination of the resistances and current sources.

That should be enough to get you started!

3. ### KFUPM University Thread Starter New Member

Apr 28, 2011
9
0
i tried but i didn't find the right answer (48V)

could you explain more plz

4. ### jegues Well-Known Member

Sep 13, 2010
735
43
If you show us your attempt it makes it alot easier for us to help you.

I'll get you started with the leftmost voltage source and resistance.

Applying ohms law we would see a current source of the value,

$I = \frac{V}{R} = \frac{120V}{20\Omega} = 6A$

The value of the parallel resistance for the transformed voltage source will be identical to its previous(before being transformed) series resistance.

5. ### jegues Well-Known Member

Sep 13, 2010
735
43
Also, there may be a mistake in the figure you've posted. Usually the positive terminal of a DC voltage source is on the end with the wider "line".

In your figure it seems to be the opposite.

6. ### KFUPM University Thread Starter New Member

Apr 28, 2011
9
0
thank you my friend i I appreciate all the work you have put in

when i converted it to be 2 resistances and voltage source i used VDR

thx again

7. ### steveb Senior Member

Jul 3, 2008
2,433
469
Are you saying the correct answer is 48V, or did you get 48V?

8. ### KFUPM University Thread Starter New Member

Apr 28, 2011
9
0
yes it is 48v
also as you said the signs should be opposite

9. ### steveb Senior Member

Jul 3, 2008
2,433
469
So, what did you get for your answer?

I ask because I did it out by two methods. Both answers agreed but it came out less than 48V.

I'm curious if you got the same answer I did.

First I did it using source transformation, and then I checked it using circuit equations. Perhaps there is an error in the schematic, as mentioned above.

10. ### KFUPM University Thread Starter New Member

Apr 28, 2011
9
0
this my final answer it is ok i check solution same final answer

look at attachment

File size:
171.9 KB
Views:
17
11. ### steveb Senior Member

Jul 3, 2008
2,433
469
OK. I just noticed that if you assume that V1 us defined backwards and V2 is correct, the answer is 48v.

Try it that way. EDIT: Ok I see that you did it that way above. Good!