大学物理实验课程绪论english

1,IntroductionofPhysicalExperiment,CenterofPhysicsExperimentSeptember,2008,2,1.WhyMustYouHavetheClassofPhysicalExperiment?2.Measurement,ErrorandUncertainty3.GraphandMethodofLeastSquares4.HowDoYourBestduringClass?,3,1.WhyMustYouHavetheClassofPhysicalExperiment?,1.1EffectsofPhysicalExperimentonScienceandTechnology1.2PurposesoftheclassofPhysicalExperiment,4,RolesofPhysicalExperiment,Physicsisasciencethathasdevelopedoutofeffortstodescribehowandwhyourphysicalenvironmentbehavesasitdoes.Theexcitingfeatureofphysicsisitscapacityforpredictingthewaynaturewillbehaveinonesituationonthebasisofexperimentaldataobtainedinanothersituation.SuchPredictionscanhaveatremendousimpactinourlives,forinthissensephysicsisattheheartofmoderntechnology.,5,1997：LaserCoolingandCapturingNeutralAtomStevenChuCohen-TannoudjiWilliamD.Phillips1998：FractionalQuantumHallEffectRobertB.LaughlinHorstL.StormerDanielC.Tsui,6,2001：Bose-EinsteinCondensationEricA.CornellWolfgangKetterleCarlE.Wieman,7,PurposesoftheClassofPhysicalExperiment,LearningofExperimentalKnowledgeTrainingofExperimentalAbilityEnhancingofExperimentalAccomplishment,8,LearningofExperimentalKnowledge,Howtolearn?Andlearnwhat?Observeandanalyzephysicalphenomena.Measurephysicalquantities.Masterbasicskillsofexperimentanddesigningideas.Haveaninsightintotheframeofphysics.,9,TrainingofExperimentalAbility,Properuseofinstrumentsbymeansoftextbooksorinstructions；Elementaryanalysisandjudgmentofphenomenabyusinglawsofphysics；Correctrecordanddisposalofdata,drawingofplotsofcurves,rationalexplanationofresults,writingofreports；Properdesignofexperimentsinaccordwithexperimentalpurposesandinstrumentsinhand.,10,EnhancingofExperimentalAccomplishment,(scientific)Style；(seriousandearnest)Attitude(ofwork)；(exploring)Spirit(ofresearchandinnovation；Virtues(ofabidingbydiscipline,cooperating,andtakinggoodcareoffacilities).,11,Hopefully,allofyoupayattentiontothecourse,andreallygetwhatyouwant!,12,2.Measurement,ErrorandUncertainty,2.1MeasurementandSignificantFigures2.2ErrorandBasicKnowledgeoftheEstimateofUncertainty,13,MeasurementandSignificantFigures,MeasurementReadingsofSignificantFiguresOperationofSignificantFiguresRulesofRoundingoffSignificantFigures,14,Measurement,Measurement:withtheaidofscientificmethods,byusingpropertoolsorinstruments,acharacterizingphysicalquantity(measuredquantities)iscomparedwiththeselectedunitofthesamekindofthephysicalquantity,andtheratioisthevalueofthemeasuredquantity.,15,Directmeasurement：todirectlycompare,suchaslength；Indirectmeasurement：tocalculatethevalueofthemeasuredquantity,withthehelpoftheknownfunctionbetweenthemeasuredquantityandthedirectmeasuredones.Value=readingnumbers(significantfigures)+unitSignificantfigurescredibledigitsdoubtabledigits,16,Readingofsignificantfigures,15.2mm15.0mm,17,Operationofsignificantfigures,Addition,subtraction：whennumbersareaddedorsubtracted，thelastsignificantfigureoccursinthefirstcolumn(countingfromright)containinganumberthatresultsfromasumofdigitsthatareallsignificant.4.1786.30+21.331.778=31.8,18,Multiplication,division：whennumbersaremultipliedordivided,thefinalanswerhasanumberofsignificantfiguresthatequalsthesmallestnumberofsignificantfiguresinanyoftheoriginalfactors.4.178101978=42.2,19,Power,extraction:anumberofsignificantfiguresintheanswerarethesameasanumberofthebase。3.253=34.3logarithm:thenumberofdigitsofthemantissahasthesamenumberof.lg1.938=0.2973lg1938=3+lg1.938=3.2973Exponent:thenumberofsignificantfiguresisthesameasthedigitsoftheexponentafterthedecimalpoint(includingthezerosnexttothedecimalpoint).106.25=1.8106,100.0035=1.008,20,Trigonometricfunction:thedigitsvarywiththesignificantfiguresoftheangle.Sin3000=0.5000Cos2016=0.9381Anexactnumberisnotsubjecttorulesofoperationofsignificantfigures.Aconstanthasthesamesignificantfiguresofthemeasuredquantitythathasthesmallestones.,21,rulesofroundingoffsignificantfigures,Ifthevalueoftheeliminatedpartislessthanahalfunitofthelastsaveddigit，thenumberinthelastdigitdoesntchange.Ifthevalueoftheeliminatedpartisgreaterthanahalfunitofthelastsaveddigit，thenumberinthelastdigitisaddedbyone.Ifthevalueoftheeliminatedpartequalsahalfunitofthelastsaveddigit，whenthenumberinthelastdigitiseven,itkeepsthesame;whenodd,itisaddedbyone.4.327494.3274.327614.3284.327504.3284.328504.328Generallyspeaking：fouroffsixup，fiveeven.,22,ErrorandBasicKnowledgeoftheEstimateofUncertainty,ErrorDisposalofrandomerrorExpressionofuncertaintyofameasuredresultCompositionofuncertaintyofindirectmeasurement,23,AstoaphysicalquantityxbeingmeasuredErrordxmeasurementvaluextruevalue,Truevalue：theactualvalueofaphysicalquantityunderacertainexperiment,Error,24,Thereexisterrorsinallmeasurements.Anerrorcanbemadesmallerandsmaller,butneverzero.Therefore,ameasurementwithoutanerrorismeaningless.,Error,25,Systematicerror,Definition：Inthecourseofmeasuringaquantitymanytimes，theabsolutevaluesandthesignsoferrorsremainunchangedorvaryinafixedwaywithmeasuringconditions.Reason：measuringinstrument,measuringway,environment,andetc.Classificationanddisposal：1quantifiedsystematicerror：revision.suchaszeropositionerrorsofascrewmicrometerandmultimeter,anderrorsduetoignoringofinnerresistors.quantifiedsystematicerror：estimateoftherangeofanerror.suchasthreadintervaltolerance.,26,Randomerror,Definition：Inthecourseofmeasuringaquantitymanytimes，theabsolutevaluesandthesignsoferrorsvaryinanunpredictablemanner.Reason：Fluctuationsofexperimentalconditionsandenvironmentalfactors.,27,(1)Theprobabilitiesofsmallerrorsaregreaterthanthoseoflargeones；(2)Thedistributionoftheerrorprobabilityisanormaldistributionfunctioniftimesofmeasurementapproachtoinfinity；(3)Cancellation:thearithmeticaverageofmeasurementvaluescaneliminateorcanceltherandomerror.,Characteristicofrandomerror,28,Degreeofdispersionofmeasuredvalues,l,29,Thisprobabilityiscalledfiducialprobability,andthecorrespondingrangeiscalledfiducialrange.,30,Ifthefiducialrangeisenlarged,thefiducialprobabilitycanincrease.,31,MeanvalueSupposethataphysicalquantityismeasuredntimes,andthemeasuredvalueisxi(i=1,2，n)Thearithmeticalaverageistakenastheoptimalmeasuredvalue.Whennapproachestoinfinity,theresultisthetruevalueofthequantity.,32,Whennisfinite,thearithmeticalaverageisnotequaltothetruevalue,andhisdeviationisasfollows：Themeaningof：theprobabilityofthequantitytobemeasuredintherangeis0.683.,33,Inphysicalexperiments，thefiducialprobabilityistakenas0.95,andthenthefiducialrangeofT-typedistributioncanbewrittenasfollowing:Ingeneral，themeasurementtimenistakenassix.,34,Expressionofuncertaintyofameasuredresult,Uncertaintyisanerrorlimitunderacertainfiducialprobability,andreflectsarangeofpossibleerror.Ingeneral,FiducialProbability:0.95!,35,TypeA:thecomponentwhichcanbeestimatedbyusingstatistics,Thetypeofuncertainty,36,TypeB:thecomponentwhichcannotbeestimatedbyusingstatistics,forexample,systematicerror.cisfiducialfactor.Whenthefiducialprobabilityis0.95,c=1.05,37,Uncertainty:Relativeuncertainty:Result:,38,Attentions：,1.Numberofsignificantfiguresofthearithmeticalaveragedoesntexceedthatofthemeasuredvalue;2.Uncertaintyandrelativeuncertaintyhaveoneortwodigitsofsignificantfigures；3.Thelastdigitofuncertaintyisevenwiththatoftheaverage.,39,Exampleone：measurementofdiameterofawirebyusingascrewmicrometer.,Datumtable,40,Solutionforexampleone：,Noneofabnormaldata,41,42,Result:,43,Calculationofuncertaintyofindirectmeasurement,Themeasuredquantityxasafunctionofdirectlymeasuredquantitiesxi：（1）foradditionorsubtraction.（2）formultiplication,division,power,orexponent.,44,Oftenusedformulas,45,Example,Allthesizesofaringaremeasuredasfollows.Please,givethefinalresultofitsvolume.,Resolution：,2.Resultinguncertainty,1.,46,3.Relativeuncertainty,4.Finalresult,47,3.GraphandMethodofLeastSquares,3.1Disposalofdatabygraphicmethod3.2LinearFittingbymethodofminimumsquares,48,2.Chooseproperscalesforaxestodeterminethesizeofcoordinatepaper.,Datatableofvoltmeter-ammetermethodforresistance,Procedureofdisposalofdatabythegraphicmethod,1.Makeatableofdata.,49,3.Marktheaxes：broadenedline，arrow，sign,name,andunit.,5.Connectthedatapointssmoothlywithalineorcurve.,4.Symbolizedatapoints.,50,6.Givealegendofthegraph.,7.Giveanameofgraph,51,:Improperfigures,52,Corrected：,53,Volt-amperecharacteristics,54,Corrected：,55,56,Supposethequantitiesx,yabidebythelinearrelationy=a+bx.xi，yii=1,.,n当Whenasumofsquaredifferencesbetweenthemeasuredyiandamountofa+bxiisminimum,thatis,aandbarefittingparameters.,LinearFittingbymethodofminimumsquares,57,58,59,Correlationcoefficientr：Exceptaandb，rmustbecalculated.r-1，1,|r|1，linearitybetweenxandyisgood;|r|0，thereisnolinearitybetweenxandy,andthelinearfittingismeaningless.Inphysicalexperiments,|r|isgreaterthan0.999.,where,60,Solutionsfora,b,andr：1.Excel;2.OriginorMatlab(7/pub/origin);3.Programswrittenbyyourself.Beforeleastsquaremethodisused,theabnormalpointsareremovedfromdata!,61,4.Howdoyourbestduringtheclass?,PreparationOperationReport,62,Preparation,Objective，Principle，Precaution。,63,Name,objective；Sketch（electricoroptical），Formula；Datatable（known,given,directly-measured,indirectly-measuredquantity,andunit）。Donotcopyprinciples！,Contentofpreparationreport：,64,Operation,Abidebyrules；Understandusageofinstruments；Dosometentativeoperationsbeforeformalmeasurements；Lookaroundandanatomizeexperimentalphenomena；Faithfullyrecorddataandphe