# Question on solution of RLC problem

Discussion in 'Homework Help' started by Hitman6267, May 29, 2010.

1. ### Hitman6267 Thread Starter Member

Apr 6, 2010
82
0

I've attached both a problem and its solution

I don't get from where did they deduce that ic(0+) = 37.4mA ?

2. ### mik3 Senior Member

Feb 4, 2008
4,846
63
It is the norton current, 30V/800R=37.5mA

3. ### Hitman6267 Thread Starter Member

Apr 6, 2010
82
0
I got how did they did the source transformation but why doesn't a part of the current go through the 800 ohm resistor

4. ### Ghar Active Member

Mar 8, 2010
655
73
The initial voltage across the capacitor is 0 so that gives zero voltage across the Norton resistor as well, meaning all the current goes through the capacitor.

The current in the inductor is the integral of voltage across it so must still be 0 if no time has passed.

5. ### Hitman6267 Thread Starter Member

Apr 6, 2010
82
0
That makes sense thank you.

Btw both of you referred to the case as being the norton equivalent, is there any significance to that ? (Other than just a name)

6. ### Ghar Active Member

Mar 8, 2010
655
73
I said Norton resistor because the actual circuit is a different configuration. In the original circuit the 800 ohm resistor of course takes all of the current.