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The impedance of a circuit having an inductance and a capacitance in parallel at the frequency at which this impedance has a maximum value. Also known as rejector impedance.
Series resonant circuits have their lowest impedance at the resonant frequency. Parallel resonant circuits have their highest impedance at the resonant frequency. This characteristic is exploited in the design of filters, oscillators and other circuits.
Inside the circuit loop between the inductor and capacitor the current will be at maximum. Outside the circuit the current through the LC tank circuit will be at minimum. It depends on where you are measuring it.
Because the series resonant circuit has the lowest possible impedance at resonance frequency, thus allowing the AC current to circulate through it. At resonance frequency, XC=XL and XL-XC = 0. Therefore, the only electrical characteristic left in the circuit to oppose current is the internal resistance of the two components. Hence, at resonance frequency, Z = R. Note: This effect is probably better seen with vectors. Clarification: Resonant circuits come in two flavors, series and parallel. Series resonant circuits do have an impedance equal to zero at the resonant frequency. This characteristic makes series resonant circuits especially well suited to be used as basic pass-band filters (acceptors). However, parallel circuits present their maximum impedance at the resonant frequency, which makes them ideal for tuning purposes.
THE PARALLEL rlc CIRCUIT IS CALLED A REJECTOR CIRCUIT BECAUSE IT REJECTS DOWN THE CURRENT. THE REASON IS AT RESONANCE THE IMPEDENCE OF THE CAPACITOR BECOMES EQUAL TO THAT OF THE INDUCTOR SO NO CURRENT FLOWS. AT LOW FREQUENCY THE CAPACITIVE REACTANCE IS LOW SO ALL THE CURRENT FLOWS THROUGH THE INDUCTOR AND WHEN THE FREQUENCY IS HIGH ALL THE CURRENT WILL FLOW THROUGH THE CAPACITOR BECAUSE AT THAT POINT THE REACTANCE OF THE CAPACITOR IS LOW. SO WE OBTAIN A V-SHAPED GRAPH WITH THE PEAK OF V INDICATING THE REJECTION OF CURRENT IN PARALLEL R-L-C CIRCUIT CIRCUIT,AT RESONANCE,IMPEDANCE IS MAXIMUM AND CURRENT IS MINIMUM.HENCE, SUCH A CIRCUIT WHEN USED IN RADIO STATIONS IS KNOWN AS REJECTOR CIRCUIT BECAUSE IT REJECTS OR TAKES MINIMUM CURRENT OF THAT DESIRED FREQUENCY TO WHICH IT RESONATES.(THIS RESONANCE IS OFTEN REFERRED TO AS CURRENT RESONANCE BECAUSE THE CURRENT CIRCULATING BETWEEN THE TWO BRANCHES IS MANY TIMES GREATER THAN THE LINE CURRENT TAKEN FROM THE SUPPLY.THE PHENOMENON OF PARALLEL RESONANCE IS OF GREAT PRACTICAL IMPORTANCE BECAUSE IT FORMS THE BASIS OF TUNED CIRCUITS IN ELECTRONICS.)A PARALLEL R-L-C CIRCUIT HAS THE PROPERTY OF SELECTIVITY I.E.IT CAN SELECT THE DESIRED FREQUENCY FOR AMPLIFICATION OUT OF A LARGE NUMBER OF FREQUENCIES SIMULTANEOUSLY IMPRESSED UPON IT.FOR INSTANCE IF A MIXTURE OF FREQUENCIES INCLUDING RESONANT FREQUENCY IS FED TO THE INPUT THEN MAXIMUM AMPLIFICATION OCCURS FOR THE RESONANT FREQUENCY.FOR ALL OTHER FREQUENCIES ,THE CIRCUIT OFFERS VERY LOW IMPEDANCE AND HENCE THESE ARE AMPLIFIED TO A LESSER EXTENT AND MAY BE THOUGHT AS REJECTED BY THE CIRCUIT.
As a parallel resonance circuit only functions on resonant frequency, this type of circuit is also known as an Rejecter Circuit because at resonance, the impedance of the circuit is at its maximum thereby suppressing or rejecting the current whose frequency is equal to its resonant frequency.
The impedance of a circuit having an inductance and a capacitance in parallel at the frequency at which this impedance has a maximum value. Also known as rejector impedance.
Series resonant circuits have their lowest impedance at the resonant frequency. Parallel resonant circuits have their highest impedance at the resonant frequency. This characteristic is exploited in the design of filters, oscillators and other circuits.
Inside the circuit loop between the inductor and capacitor the current will be at maximum. Outside the circuit the current through the LC tank circuit will be at minimum. It depends on where you are measuring it.
For a particular frequency if the current or the voltage of the circuit is Maximum or Minimum then that circuit is said to be in resonance .
Because the series resonant circuit has the lowest possible impedance at resonance frequency, thus allowing the AC current to circulate through it. At resonance frequency, XC=XL and XL-XC = 0. Therefore, the only electrical characteristic left in the circuit to oppose current is the internal resistance of the two components. Hence, at resonance frequency, Z = R. Note: This effect is probably better seen with vectors. Clarification: Resonant circuits come in two flavors, series and parallel. Series resonant circuits do have an impedance equal to zero at the resonant frequency. This characteristic makes series resonant circuits especially well suited to be used as basic pass-band filters (acceptors). However, parallel circuits present their maximum impedance at the resonant frequency, which makes them ideal for tuning purposes.
THE PARALLEL rlc CIRCUIT IS CALLED A REJECTOR CIRCUIT BECAUSE IT REJECTS DOWN THE CURRENT. THE REASON IS AT RESONANCE THE IMPEDENCE OF THE CAPACITOR BECOMES EQUAL TO THAT OF THE INDUCTOR SO NO CURRENT FLOWS. AT LOW FREQUENCY THE CAPACITIVE REACTANCE IS LOW SO ALL THE CURRENT FLOWS THROUGH THE INDUCTOR AND WHEN THE FREQUENCY IS HIGH ALL THE CURRENT WILL FLOW THROUGH THE CAPACITOR BECAUSE AT THAT POINT THE REACTANCE OF THE CAPACITOR IS LOW. SO WE OBTAIN A V-SHAPED GRAPH WITH THE PEAK OF V INDICATING THE REJECTION OF CURRENT IN PARALLEL R-L-C CIRCUIT CIRCUIT,AT RESONANCE,IMPEDANCE IS MAXIMUM AND CURRENT IS MINIMUM.HENCE, SUCH A CIRCUIT WHEN USED IN RADIO STATIONS IS KNOWN AS REJECTOR CIRCUIT BECAUSE IT REJECTS OR TAKES MINIMUM CURRENT OF THAT DESIRED FREQUENCY TO WHICH IT RESONATES.(THIS RESONANCE IS OFTEN REFERRED TO AS CURRENT RESONANCE BECAUSE THE CURRENT CIRCULATING BETWEEN THE TWO BRANCHES IS MANY TIMES GREATER THAN THE LINE CURRENT TAKEN FROM THE SUPPLY.THE PHENOMENON OF PARALLEL RESONANCE IS OF GREAT PRACTICAL IMPORTANCE BECAUSE IT FORMS THE BASIS OF TUNED CIRCUITS IN ELECTRONICS.)A PARALLEL R-L-C CIRCUIT HAS THE PROPERTY OF SELECTIVITY I.E.IT CAN SELECT THE DESIRED FREQUENCY FOR AMPLIFICATION OUT OF A LARGE NUMBER OF FREQUENCIES SIMULTANEOUSLY IMPRESSED UPON IT.FOR INSTANCE IF A MIXTURE OF FREQUENCIES INCLUDING RESONANT FREQUENCY IS FED TO THE INPUT THEN MAXIMUM AMPLIFICATION OCCURS FOR THE RESONANT FREQUENCY.FOR ALL OTHER FREQUENCIES ,THE CIRCUIT OFFERS VERY LOW IMPEDANCE AND HENCE THESE ARE AMPLIFIED TO A LESSER EXTENT AND MAY BE THOUGHT AS REJECTED BY THE CIRCUIT.
The resonance effect of the LC circuit has many important applications in signal processing and communications systems.The most common application of tank circuits is tuning radio transmitters and receivers. For example, when we tune a radio to a particular station, the LC circuits are set at resonance for that particular carrier frequency.A series resonant circuit provides voltage magnification.A parallel resonant circuit provides current magnification.A parallel resonant circuit can be used as load impedance in output circuits of RF amplifiers. Due to high impedance, the gain of amplifier is maximum at resonant frequency.Both parallel and series resonant circuits are used in induction heating.LC circuits behave as electronic resonators, which are a key component in many applications:AmplifiersOscillatorsFiltersTuners
The properties of a series alternating-current L-R-C circuit at resonance are:the only opposition to current flow is resistance of the circuitthe current flowing through the circuit is maximumthe voltage across the resistive component of the circuit is equal to the supply voltagethe individual voltages across the inductive and capacitive components of the circuit are equal, but act in the opposite sense to each otherthe voltage appearing across both the inductive and capacitive components of the circuit is zeroif the resistance is low, then the individual voltages appearing across the inductive and capacitive components of the circuit may be significantly higher than the supply voltage
XL=Xc is the resonance condition for an RLC circuit
Resonant means something vibrates at a given frequency. Usually if you can get an object to resonate at its resonant frequency - it will disintegrate ! For example - if you tap a wine-glass, it 'rings' - that's it's resonant frequency. Now - take a speaker and play the exact frequency through it, while holding it close to the glass - after a few seconds it will shatter because the glass vibrates too fast.
IN A SERIES RLC CIRCUIT XL=XC.THEREFORE, IMPEDANCE Z IS MINIMUM AND Z=R.SINCE THE IMPEDANCE IS MINIMUM,CURRENT IN THE CIRCUIT WILL BE MAXIMUM. XL=XC MULTIPLYING BY MAX. CURRENT Io (AT RESONANCE) ON BOTH SIDES, WE GET, IoXL=IoXC I.E. Vlo=Vlc(POTENTIAL DIFFERENCE ACROSS INDUCTANCE IS EQUAL TO THE POTENTIAL DIFFERENCE ACROSS CAPACITANCE AND BEING EQUAL AND OPPOSITE THEY CANCEL EACH OTHER.)SINCE Io IS MAXIMUM,Vlo AND Vco WILL ALSO BE MAXIMUM.THUS,VOLTAGE MAGNIFICATION TAKES PLACE DURING RESONANCE.HENCE,IT IS ALSO REFERRED TO AS VOLTAGE MAGNIFICATION CIRCUIT.