An important property of this circuit is its ability to resonate at a specific frequency, the resonance frequency, f0. It is the frequency the circuit will naturally oscillate at if not driven by an external source. A key parameter in filter design is The fractional bandwidth is also often stated as a percentage. 8.9 is also called the selectivity curve of the Bandwidth of RLC Circuit. The full swinging action would continue.A tank circuit is similar to this swing example. The supply voltage is 500 μV and the Q of this circuit is 100. The total voltage which is defined as the resonant angular frequency of the circuit. The resonance frequency, The critically damped response represents the circuit response that decays in the fastest possible time without going into oscillation. In this article, angular frequency, ω0, is used because it is more mathematically convenient. The first evidence that a capacitor and inductor could produce electrical oscillations was discovered in 1826 by French scientist Electrical "resonator" circuit, consisting of inductive and capacitive elements with no resistance A circuit with a value of resistor that causes it to be just on the edge of ringing is called Circuits with topologies more complex than straightforward series or parallel (some examples described later in the article) have a driven resonance frequency that deviates from The resonance effect can be used for filtering, the rapid change in impedance near resonance can be used to pass or block signals close to the resonance frequency.

The name RLC circuit is derived from the starting letter from the components of resistance, inductor, and capacitor. The resonance of a series RLC circuit occurs when the inductive and capacitive reactances are equal in magnitude but cancel each other because they are 180 degrees apart in phase.The sharp minimum in impedance which occurs is useful in tuning applications. Minimum line current flows at the resonant frequency of this tuned circuit.The resonant frequency can be found by observing the minimum value in the line current. A circuit containing this periodic changing current is said to be The periodic current changes in the circuit can be described as The amplitude, or size, of each successive oscillation, decreases due to the resistance.Compare the oscillators of a tank circuit to a child on a swing. The Q of a circuit can be found using the formula:Where Q is the quality factor, XL is the inductive reactance at resonance, and R is the resistance.Example: In a series circuit, the inductive reactance is 1000 ohms at resonance, and the resistance of the wire of the coil is 10 ohms. Figure 11 is a band-stop filter formed by a parallel LC circuit in series with the load. In the series configuration, resonance occurs when the complex electrical impedance of the circuit approaches zero. The power consumed by the circuit is equal to the product of volts time’s amperes.In an ac circuit containing inductance only, the current lags the voltage by an angle of 90 degrees. Notice, on the graph, that the impedance of the circuit is minimum at resonance.Note also that maximum current flows at resonance. Finally, defining the natural angular frequency as It is still possible for the circuit to carry on oscillating (for a time) after the driving source has been removed or it is subjected to a step in voltage (including a step down to zero).
The complex admittance of this circuit is given by adding up the admittances of the components: Q has no units. Converting angular frequency (in radians per second) into frequency (in hertz), one has The transmission line as parallel planes, stripes and microstripes.
The total impedance is then given by: It shows a parallel tuned circuit. In this case it is the natural undamped resonant frequency:Furthermore, the exact maximum impedance magnitude is given byIn the same vein, a resistor in parallel with the capacitor in a series LC circuit can be used to represent a capacitor with a lossy dielectric.