Question on solution of RLC problem

Discussion in 'Homework Help' started by Hitman6267, May 29, 2010.

  1. Hitman6267

    Thread Starter Member

    Apr 6, 2010
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    0
    Capture.PNG
    solution.PNG

    I've attached both a problem and its solution

    I don't get from where did they deduce that ic(0+) = 37.4mA ?
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    It is the norton current, 30V/800R=37.5mA
     
  3. Hitman6267

    Thread Starter Member

    Apr 6, 2010
    82
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    I got how did they did the source transformation but why doesn't a part of the current go through the 800 ohm resistor
     
  4. Ghar

    Active Member

    Mar 8, 2010
    655
    72
    The initial voltage across the capacitor is 0 so that gives zero voltage across the Norton resistor as well, meaning all the current goes through the capacitor.

    The current in the inductor is the integral of voltage across it so must still be 0 if no time has passed.
     
  5. Hitman6267

    Thread Starter Member

    Apr 6, 2010
    82
    0
    That makes sense thank you.

    Btw both of you referred to the case as being the norton equivalent, is there any significance to that ? (Other than just a name)
     
  6. Ghar

    Active Member

    Mar 8, 2010
    655
    72
    I said Norton resistor because the actual circuit is a different configuration. In the original circuit the 800 ohm resistor of course takes all of the current.
     
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