Kirchoff's Law problem

1. May 11, 2014

Regtic

http://i.imgur.com/EFciS60.png

How do you do part e? Also can someone explain why the current I3 isn't 0 if the switch has been closed for a long time? Doesn't it behave like a short circuit if the switch is closed because the capacitor becomes fully charged and the current becomes zero ish?

Last edited: May 11, 2014
2. May 11, 2014

phinds

This is simple circuit analysis. You have to show an attempt yourself.

If the switch has been closed for a long time that current is zero.

No, it becomes an OPEN circuit and the current is zeor-ish.

Yes, and you should have shown some attempt at your own work in the homework template.

3. May 11, 2014

Regtic

Oh this was from a test, I could have shown it but I got 5.5/10 on it so it wasn't very useful.

4. May 11, 2014

Regtic

5. May 11, 2014

Regtic

What's the difference? I thought they were the same thing? They both mean the switch is open no?

Last edited: May 11, 2014
6. May 11, 2014

phinds

Do you understand that a short circuit and an open circuit are not the same thing? Sloppy terminology results from and/or causes sloppy thinking, so saying that a short circuit and an open circuit are the same thing is not a good idea.

7. May 11, 2014

Regtic

Ya no kidding...

8. May 11, 2014

Regtic

Do you guys think these answers are correct? I posted the problem to chegg but I have like 3 different answers. I think this one might might be legit, but I don't know if it's really discharging or not. I think it's charging up because it's an open circuit and current is trying to pass through it but it's fully charged. I don't understand what he did for part D so I think that's wrong, but everything else is legit.

(or on imgur)
http://i.imgur.com/KxAoeQ4.jpg?2

Last edited: May 11, 2014