1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: S domain analysis problem, just need a little help

  1. Mar 4, 2012 #1
    Okay i need to find expressions for v1 and v2 and im using nodal analysis:

    these are not the final the equations just initial equations by first look

    I am good finding expression for v1,
    (2/s)-(v1/1)-((v1-v2)/(2/s)) = 0

    Where i am stuck is with the current source and 2 ohm res. in series

    For v2,
    ((v1-v2)/(2/s))-(v2/2s)-(v2/2)-(5/s) = 0 this is my derivation that im unsure of

    the reason i think this is wrong for v2 is in my head i see instead of v2/2 - 5/s i see something like ((v2-v)/2)-(5/s)? where v is voltage between current source and res

    Can anyone help me understand where im right or wrong thanks

    **BTW see attachment for circuit**

    Attached Files:

  2. jcsd
  3. Mar 4, 2012 #2


    User Avatar

    Staff: Mentor

    For nodal analysis you're only concerned with summing the currents. The 2Ω resistor in series with the 5u(t) current source is not going to alter that current that it pulls from the V2 node. So ignore the resistor!

    FYI, your entries for the capacitor impedance look a bit off. 1/(s*200 mF) should yield something like 5/s.
  4. Mar 4, 2012 #3
    so would v2 be:

    ((v1-v2)/(5/s)) - v2/2s - 5/s?

    my mistake on the cap transformation it is 5/s which is equal to 1/0.2s my bad
  5. Mar 4, 2012 #4


    User Avatar

    Staff: Mentor

    That looks fine :smile:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook