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What is resonant circuit?

  1. Nov 26, 2005 #1
    What is resonant circuit? and specifically what is RLC circuit?
    THANX ALOT!:smile:
  2. jcsd
  3. Nov 26, 2005 #2


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    An RLC circuit is a kind of electrical circuit composed of a resistor (R), an inductor (L), and a capacitor (C). For more info read http://en.wikipedia.org/wiki/RLC_circuits


    Additional info >>> http://hyperphysics.phy-astr.gsu.edu/hbase/electric/serres.html
    Last edited: Nov 26, 2005
  4. Nov 27, 2005 #3
    A circuit that has a set capasitance and Inductance, will "Resonate" at a set frequency of AC Current. Resonace occurs when Capasitive Reactance ( XC= 1/2pieFC) and Inductive reactance (XL = 2pieFL) (L = Inductance in Henrys, C = Capasitance in Farads) are equal to each other. To understand how this really works, you need to know the effects of inductance and capasitance on an AC Circuit. Inductance changes the phase angle of an AC sine wave by increasing the angle, Capasitance reduces the angle. When AC meets a capasitance or inductance, it reacts with them, and produces a resistance that only an AC current at the given frequency would see. When the frequency reachs the resonate level (given by Fr = 1/2pie(LC)^1/2), the reactances cancel each other out and the AC current basicly ignores them and resistance is figured by the Ohmic resistance of the coil that provides the inductance.

    Circuits that use resonance in everyday use:
    AM/FM recievers
    Class-C Amlifiers
    Metal detectors
  5. Nov 29, 2005 #4
    so capacitance reduce the phase angle and inductance increase the phase angle? and by the way,

    here is what I think inductors do
    they allow current to follow across it and store energy by creating magatic field.

    Is this correct, what other basic thing does inductors do?
  6. Nov 29, 2005 #5


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    Yes that is correct. It stores energy in a magnetic field that is created by current flowing through its coils.

    I'm sure after you read this, you will have a better understanding of inductors and be able to answer your second question.

    Please also read this thread. I've attempted to only provide a very brief intro into the workings of the inductor. Please note how I often compare it to the capacitor.
    Last edited: Nov 29, 2005
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