# Homework Help: Circuit Analysis : Using Kirchoffs

1. Aug 30, 2011

### gatsbycollege

1. The problem statement, all variables and given/known data
http://img202.imageshack.us/img202/939/95788682.jpg [Broken]

Find Vo
Vo = -50V (given answer by my prof)

2. Relevant equations
KVL
(Series) V=V1+V2
(Parallel) V=V1=V2
KCL
Current toward the node = Current Away from the node
V=IR

3. The attempt at a solution

i tried to solve for the i in the left ckt
i=(6v+0.004Vo)/2k <-- 6v is in series with 0.004Vo (i think)

by KCL at the right
25i - (Vo/40k) - (Vo/10k) = 0 <--- 40k and 10k is in parallel so Voltage would be equal
the substitute terms

25((6v+0.004Vo)/2k) - (Vo/40k) - (Vo/10k) = 0
Vo = 1kV <--- actually is not right XD

so there it is,, what did i miss?

Edit : (50v change to 6v)

Last edited by a moderator: May 5, 2017
2. Aug 30, 2011

### Staff: Mentor

Where does the 6V come from in your equations? The diagram shows a 50V source.

Also, the potential across the 2k resistor appears to be 50V - 0.004Vo. "Walk" around the loop in the direction of the current and it goes: 50V - i*2k - 0.004Vo = 0.

3. Aug 30, 2011

### gatsbycollege

Aw.. my mistake,, 50v at the left should be 6v Sorry :tongue:

Edit: So there it is i changed the circuit.

4. Aug 30, 2011

### gatsbycollege

by referring to what you said sir,

i= (6v-0.004Vo)/ 2k

BY KCL
then 25(i)-Vo/40k - Vo/10k = 0
then substitute
25((6v-0.004Vo)/2l)) -Vo/40k -Vo/10k = 0
Therefore

Vo = 428.57V

Hmm still not the right answer ?

5. Aug 30, 2011

### Staff: Mentor

Or perhaps it's the right answer to the wrong problem

Your calculations appear to be sound for the circuit shown. Can you verify that the circuit matches the problem given?

6. Aug 30, 2011

### gatsbycollege

i double check the given here in my copy.. the circuit is right.. but not so sure about my computation :tongue:

so what do you think.. maybe the answer given by my prof is wrong? Vo = -50V

7. Aug 30, 2011

### Staff: Mentor

As I said, your computation looks correct for the circuit given. It is possible that your Prof was incorrect (or was misinterpreted?).

8. Aug 30, 2011

### gatsbycollege

Ahm ok Thx for Helping me