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Homework Help: RC Circuits with switch

  1. Mar 16, 2010 #1
    1. The problem statement, all variables and given/known data
    i need to find the Vs(t) and Vc(t)

    http://img32.imageshack.us/img32/9071/circuiten.jpg [Broken]

    3. The attempt at a solution
    since there is a switch i used two cases to find the Vc
    one with switch on and switch off
    switch on
    http://img704.imageshack.us/img704/6180/switchon.jpg [Broken]
    and switch off
    http://img265.imageshack.us/img265/3259/switchoff.jpg [Broken]

    but im lost after this...
    help me!!
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Mar 16, 2010 #2


    User Avatar

    Staff: Mentor

    The cap still needs to be there with the switch ON.

    Write the KCL equation for the node at the top of capacitor (with the bottom of the cap being the common "ground" node), and solve the resulting differential equation, using the initial conditions from when the switch was open (assume the switch is closed at t=0). Show us your work, so we can help you more if you need it.
    Last edited by a moderator: May 4, 2017
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