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1、示波器的使用ApplicationofOscilloscopeTheLabcenterofphysicsBasicstructure返回oscilloscopetubeCircuitelectrongunelectronbeamLeveldeflectorverticaldeflectorFluorescentscreendisplayprincipleofOscilloscopesinusoidalwavesawtoothwaveEvenrotationofthedrum–evenmotionoftheelectronbea
2、malongthex-direction.Motionofthepeniny-direction–deviationofthebeaminy-directionproportionaltothemeasuredvoltage.Aquestion:Theelectronbeammovingalongx-directionreachestheendofthescreenatsomepointandhastojumpbackandstartwritingagainfromthebeginningofthescreen. Howcom
3、ethatyounormallyonlyseeonecurveonthescreenatanytime? Bytheway,howfastdoesthebeamgofromlefttoright?Theansweristriggering. Afterdrawingonecurve(sinusoidal,triangular,square…)onthescreentheelectronbeamreturnsbacktoitsstartingpoint,butitdoesnotstartdrawinganothercurve,b
4、eforethevoltagereachessomepresetvalue–triggerlevel.triggerlevelLissajousFigures李薩如圖線與頻率比HorizontalintersectionVerticalintersectionFunctiongenerator空氣中聲速的測量MeasurementofSoundVelocityinAirTheLab'centerofphysicsIntroductionAcousticsmaybedefinedasthegeneration,transmiss
5、ion,andreceptionofenergyintheformofvibrationalwavesinthematter.Astheatomsormoleculesofafluidorsolidaredisplacedfromtheirnormalconfiguration,aninternalelasticrestoringforcearises.Examplesincludingthetensile(張力)forceproducedwhenaspringisstretched.Itisthiselasticrestor
6、ingforce,coupledwithinertia(惰性)ofthesystem,thatenablesmattertoparticipate(參與)inoscillatoryvibrationsandtherebygenerateandtransmitacousticwaves.Themostfamiliaracousticphenomenonisthatassociatedwithofsound.Fortheaverageyoungperson,avibrationaldisturbanceisinterpreteda
7、ssoundifitsfrequencyliesintherangeofabout20to20000Hz.Howeverinabroadersenseacousticalsoincludestheultrasonicfrequenciesabove20000Hzandtheinfrasonicfrequenciesbelow20Hz.Themeasurementofspeedofsoundisofinterestingforunderstandingthemainpropertyofsound.Onecaneasilyobta
8、inthevelocityofsoundthroughthefollowingexpression:Purpose學(xué)會(huì)用不同的方法測定空氣中的聲速。掌握數(shù)字式函數(shù)發(fā)生器、示波器的使用方法。學(xué)會(huì)用逐差法處理測量結(jié)果，并對結(jié)果的不確定度進(jìn)行分析。Experimentalmetho
