# Homework Help: Help finding Vc(o-)

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1. Oct 14, 2016

### sammyqw

1. The problem statement, all variables and given/known data
find Vc(0)

2. Relevant equations
Node analysis , ohms law

3. The attempt at a solution

Hi, I'm trying to find Vc(0). I used node analysis but I'm stuck in eq 1. I'll appreciate if someone can give me some suggestions. Thanks

2. Oct 14, 2016

### Staff: Mentor

Looks like you need to replace Vo with something. Go back to your schematic and see if you can express Vo in terms of the other quantities pertaining to the branch it's in.

3. Oct 14, 2016

### sammyqw

Can I replace Vo with V-10/25 ?

4. Oct 14, 2016

### Staff: Mentor

Do you mean (V-10)/25? (Order of operations is important). No, that would be the branch current flowing from v towards the 10 V source. But that's a start. What would be Vo in terms of that current?

5. Oct 14, 2016

### sammyqw

it would be some current i = Vo/20 ?

6. Oct 14, 2016

### Staff: Mentor

That's the idea. But you've already identified the branch current in post #3.

7. Oct 14, 2016

### sammyqw

Can I do i=10/25 = 0.4A then find Vo= (0.4)20 =8V and then just replace it in my equation 2?

8. Oct 14, 2016

### Staff: Mentor

No because the battery voltage is not across the branch. What is an expression for the branch current (you wrote one as a term in your node equation!)?