OLbecause : ->>1So,we get:YL(oL-ir,)(LICZZparaller1parallel=ri +i(oL -r +i(oL-00SO:LICOL.paralleoC@-arctanr'+(oL --rL0phaseanglePhase difference
: 1 L r L because ) 1 ( ~ / C r i L L C Z L parallel + − So , we get： so： L r C L 1 arctan − − ) 1 ( ) 1 ( )( ~ C r i L C L ir Z L L parallel + − − = 2 2 ) 1 ( / C r L L C Z L parallel + − phase angle Phase difference
when QLparallel circuit is resonant now.oCWhy?1)The resonant frequence fo:LICL/Cfo= 2元/LCZparallerr(oLOCL2)whenthe circuitisZwhole = R+parallel resonant,thercwhole impedance Z:
when 0 1 − = C L LC f 2 1 0 = r C L Z R L whole = + parallel circuit is resonant now. 1)The resonant frequence f0 : 2) when the circuit is parallel resonant , the whole impedance Z : L L parallel r L C C r L L C Z / ) 1 ( / 2 2 = + − Why?
Characteristicsof RLCSeriesresonantcircuit1:Therearesamephase9Ron currentandvoitageofLC2:lmpedancebetweenCand D is minimum3:Currentis maximumDZ= R+r+i(oL-=R+rOCZ..CD=r+i(oLseriesC
Characteristics of RLC Series resonant circuit : R L r C 1:There are same phase on current and voltage of LC 2:Impedance between C and D is minimum 3:Current is maximum R r C Z = R + r + i L − ) = + 1 ( ~ r C ZseriesCD = r + i L − ) = 1 ( ~ A C D
Characteristics of RLC parallel resonant circuit1:There are same phase on current and voltage onLOACR2:lmpedance Z(parallel)betweenCandDismaximumL3:votagebetweenCandDismaximumD1LICL/CZfo=parallel2元VLCrLOLO
R L C r 1:There are same phase on current and voltage on LC 2:Impedance Z(parallel) between C and D is maximum 3:votage between C and D is maximum L L r L C C r L L C Z / ) 1 ( / 2 2 parallel = + − Characteristics of RLC parallel resonant circuit : A C D LC f 2 1 0 =
Amplitudemethodforseriescircuit3Design scheme for measuring and drawing up Circuit diagramSeries resonant circuitRCAoscilloscope12345HZPFrequenceadjustMOD-500BCH1Sine Signal generatorsteps:1ChooseR?and setL=7mh,set C=?And write downthevalue ofthe capacitance2Connect circuit according to the circuit diagram that you design as above.3 Adjustfrequence and observethewaveform ontheoscilloscope,whenAmplitudeismaximum,write downthevalue ofthefrequence4Changethevalueof C to measure frequenceagainforsixtimes
3 Design scheme for measuring and drawing up Circuit diagram R C r L A B C D 12345HZ Frequence adjust Sine Signal generator CH1 oscilloscope steps： 1 Choose R? and set L=7mh,set C=? And write down the value of the capacitance 2 Connect circuit according to the circuit diagram that you design as above. 3 Adjust frequence and observe the wave form on the oscilloscope，when Amplitude is maximum, write down the value of the frequence 4 Change the value of C to measure frequence again for six times 50Ω Series resonant circuit Amplitude method for series circuit