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Homework Help: Phasor approach question

  1. Nov 6, 2007 #1
    [SOLVED] phasor approach question

    using phasor approach, determine the current i(t) in a circuit described by the integrodifferential equation: 4i + 8integral(idt) - 3di/dt = 50cos(2t + 75*)
    the right side is so easy to convert to phasor form, but how can i convert the left side or how to solve such a problem?
  2. jcsd
  3. Nov 7, 2007 #2
    dear it is simple.
    just write I=dq/dt.you will get a second order differential equation.
    you can solve it easily.
  4. Nov 7, 2007 #3
    also integral(Idt)=q.
  5. Nov 9, 2007 #4


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    Staff Emeritus
    Science Advisor

    I think the point is to use the phasor format, and realize the for the phasor [tex]Ae^{i\omega{t}}[/tex], that

    [tex]d/dt(e^{i\omega{t}})\,=\,i\omega{e^{i\omega{t}}}[/tex], and

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