RLC Circuit Current

Hi all,

I need help with the first question from this problem sheet I am doing. Of course I am not asking anyone to just post the answer, but some guidance in the right direction would be appreciated. That way I can attempt it, and post my answer for scrutinizing ...

Question:



Thank you.

 

Hi WBahn,

Thanks for your reply.

I think the lecturer only wants a brief description of what happens, and not a complex mathematical answer.

Of course I am able to provide you with what I think:

To begin with, for part a), I wrote:

When voltage is first applied after closing the switch (at t=0), the inductor impedes current flow in the circuit, so the current = 0. After time t=0, the current will follow a second order natural response characteristic as shown below

((P.S: I may be also interested in the mathematical answer later on.))

 

Hi WBahn,

Thanks for your reply.

I will post my answers for b) once I get home, are you able to just write the characteristic equation for part A or describe it so I know whether my answer is correct? Thanks.

 

Thanks. I only asked if you could do that so it would save time - as this is due very soon. (If I were to cheat with this question, I would only be cheating myself.)

Anyway, I have scanned my (mathematical) solutions for part a) and part b).

I will also upload the written explanation for part b) as I said yesterday.

 

Solutions:

Part b) written answer:

As soon as both s1 and s2 are closed (at t=0), the current will be equal to V(0)/R, as the infinite instantaneous impedance of the inductor will act as an open circuit.

Part a) & b) mathematical answers:

http://postimg.org/image/somif17fl/

EDIT: Realized the silly mistake in part b) where I did the parallel impedance wrong. (Ignore that.)

 

Bump...... (>10char)