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# circuit problem Watch

1. Hello. I have got this problem here that i cant crack. The first thing that gets me stuck is finding resistnace for capacitor and inductor. Rc=1/jwC (dont know the frequancy to find w) and same for Rl=jwL. I am a bit confused in where should i start. All i managed was to try node analysis and KVR which gave me too many unknowns...

the problem goes like this
1.The circuit has been in steady state for a long time before the switch closes at t=0.

a.) Find the value of the capacitor voltage(Vc) and the current through the inductor(Il) just after switch closes at t=0.

b.)What are the final values of Vc and Il, after the transient have died down?
I believe Vc=0 but i am unsure about the Il...

2. (Original post by Patrick.Mccullen)
Hello. I have got this problem here that i cant crack. The first thing that gets me stuck is finding resistnace for capacitor and inductor. Rc=1/jwC (dont know the frequancy to find w) and same for Rl=jwL. I am a bit confused in where should i start. All i managed was to try node analysis and KVR which gave me too many unknowns...

the problem goes like this
1.The circuit has been in steady state for a long time before the switch closes at t=0.

a.) Find the value of the capacitor voltage(Vc) and the current through the inductor(Il) just after switch closes at t=0.

b.)What are the final values of Vc and Il, after the transient have died down?
I believe Vc=0 but i am unsure about the Il...

I think the way to do this one is to say that when the switch is first thrown, the increase in current dI/dt is very large. Put f=infinity.
When the circuit reaches a steady state, f=0.
It's a case of two extremes. There is no stable frequency.
It also simplifies the maths.
3. (Original post by Stonebridge)
I think the way to do this one is to say that when the switch is first thrown, the increase in current dI/dt is very large. Put f=infinity.
When the circuit reaches a steady state, f=0.
It's a case of two extremes. There is no stable frequency.
It also simplifies the maths.
ahhhh Thank you!

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