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Homework Help: Inverse laplace transform

  1. Nov 1, 2011 #1
    1. The problem statement, all variables and given/known data

    Derive an equation to represent the current flowing in an RLC circuit where R=12 L=1.2 C=30microfrards with an impulse voltage input. Assume zero conditions when the switch is closed.

    2. Relevant equations

    3. The attempt at a solution
    I have used the voltage to equal 1, laplace transformed the RLC values and started from basic Kirschoffs law to give
    I= s/(1.2s^2+12s)+1

    To complete this I know I need to inverse laplace it but cannot get this equation into a format to do it. Can anyone please help before I pull my hair out how to do this??
  2. jcsd
  3. Nov 1, 2011 #2


    User Avatar
    Gold Member

    1/(1.2s + 12) = (1/1.2) / (s+12/1.2) is of the form a / (s+b) which can be found on any standard table of inverse laplace transforms.

    The inverse laplace transform of 1 is the dirac delta function.
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