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Help with RLC circuit

  1. Apr 18, 2006 #1
    i have a question where
    s1,2=(-4 (+-) j3) 10^3
    are roots of a second order D.E of a series RLC ckt
    where s1,2=(-z (+-) (z^2 -1)
    (z is zeta)
    now from
    s1,2=(-4 (+-) j3) 10^3 ,its showing roots of underdamped ckt(complex nd conjugate)
    but when i solve eq. z gives 2 values(but z must be less than 1 nd gr8er than 0 acc. 2 condition of underdamped ckt)
    help plz
  2. jcsd
  3. Apr 18, 2006 #2


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    The roots of a second order system are:
    [tex]s_{1,2} = -\zeta \omega_n \pm j\omega_n \sqrt{1 - \zeta^2}[/tex]
    where [tex]\omega_n[/tex] is the undamped natural frequency and [tex]\zeta[/tex] is the damping coefficient.
    Last edited by a moderator: Apr 19, 2006
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