# start off on s-domain

Discussion in 'Homework Help' started by deathztm, Oct 4, 2016.

1. ### deathztm Thread Starter New Member

Oct 4, 2016
2
0

Hi guys, i was approaching on this question, was wondering if the approach is correct by redrawing the circuit. Annotating V1(0) as 20V and V2(0) as 10V through conversion? is the flow of the approach correct? then i will just have to solve for A and B.

Last edited: Oct 4, 2016
2. ### MrAl Distinguished Member

Jun 17, 2014
3,620
760
Hello,

You did not label where you are saying I2 is flowing, so that leaves us to guess.
Lucky this is a simple problem, so if you mean I2 is flowing through the first resistor (connected to the 10 amp source) then yes you are correct so far. That is taking the conventional current flow direction as flowing from C1 to C2 through that first resistor (left to right through that first resistor). It also helps to label the parts R1, R2, etc.
Note i am going only by the final result you got so far.

3. ### deathztm Thread Starter New Member

Oct 4, 2016
2
0
sorry for the lack of labelling. thank you for the confirmation, will continue to solve it.

4. ### MrAl Distinguished Member

Jun 17, 2014
3,620
760
Hi,

No need to be sorry, just remember that the better you present your question the more likely you are to get help with it because people will understand your question better.

Good luck in getting the rest of the way, but i dont think you'll have a problem since you got this far.

5. ### RBR1317 Active Member

Nov 13, 2010
380
70
Was hoping the TS would have posted the final solution since I seldom (if ever) try to obtain the time-domain solution from the inverse Laplace transform. So here are the s-domain node equations for the stated problem.

Used Maple to take the inverse transform back to the time-domain solution. However, Maple added a feature that I have not seen before: Dirac(t). Have been unable to determine the purpose for the Dirac(t) function as given. Perhaps it is just a mathematical nicety that has no practical purpose in terms of the electric circuit?

The reference book "Laplace Transform Tables" by McCollum & Brown, 1965, has the following transform pair, with no Dirac(t) shown, which confuses me even more.