(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The problem is:

After being closed for along time, the switch shown in figure 1 opens at t=0. Find IA for all time.

2. Relevant equations

I believe it would be i(t)=Ioe^(-t/(CReq)) or i(t)=(Q/P)+Ae^(-Pt)

Q/p=Vo/r and 1/p is time constant or t/(CReq)

3. The attempt at a solution

I find that if i label the inductor as Vc i find the voltage as 0 at time 0 because the capacitor becomes a short over a long period of time. I get what is in t<0 and when t>0 . I believe i need to find Req but the problem is how do i find that with the wire between the two resistors? Or is it just the 1k ohms anyway? After finding Req i know that I=if+in and in=Ke^(t/(CReq). t>0 and if=10/2000=1/200 so i=(1/200)+Ke^(t/(CReq) t>0 now i think i need to find out the current so that i can have whatever current i get say B so B=1/200 + K the K = B-1/200

so that it means i=(1/200)+(K)e^(t/CReq) Then using B (current) for all t i=B+B(1-e^(-t/CReq)u(t)

So how do i find what i called B and how do i find the original Req?

Thanks to whoever can help me. Also i placed the original diagram, the t>0 and t<0 diagrams as well. Thanks again

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: RL RC circuit

**Physics Forums | Science Articles, Homework Help, Discussion**