mesuretheresistanceviathewheastonebridge电桥法测电阻实验报告英语

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1、MeasuretheResistanceviatheWheastoneBridge1.Thepurpose:i.TounderstandtheprincipleandcharacteristicsoftheWheatstonebridge・ii.Tounderstandtheconceptofsensitivityofbridge.iii.Learnthe"exchangemeasuremethocT：withwhichtoeliminatethesystemerror.2.Theapparatu

2、s:Unknownresistances;DCpowersupply;galvanometer;resistorbox;variableresistor;switchandotherelectricalcomponents;electricalbridge.3.Theories:l)TheprincipleandthestructureoftheWheatstonebridgeWhenUc二UdR亡R02)ThesensitivityoftheWheatstonebridgeBecauseofth

3、esensitivityofthegalvanometerislimited,thecurrentthroughthegalvanometerisnottrulyzero,andthegalvanometercannotefficientlymeasureit.Thesensitivityofthebridgeisdefinedastheratiobetweenthedeflectionofthegalvanometer,Ad,andthecorrespondingrelativevalueofR

4、o・△Ro/Ro2)The"exchangemeasuremethocT.ExchangethepositionsofR1andR2,orROandRx,andadjustingROtoRO:thebridgecangetanewbalaneedstate,andRCombinethisequationwithRx=—Rq,wecanget:RoRoThisequationhasnothingtodowithRiandR2.Inthiswaywecanmaketheerroronlyrelatet

5、otheinstrumenterrorofRo,whichistheinstrumenterrorofresistorbox.1.Theprocedures:1)Usesimplyconstructedbridgetomeasurethemetalfilmresistor.ConnectthecircuitandmeasuretheresistancethenexchangeRoandRxmeasuretheresistaneeagain.Thekeypoints:Findthebalaneepo

6、int.ii

7、o二apparatus)2+(AR；)2TherelativeuncertaintyofRxis:2)Usebox-bridgetomeasuretheresistance.i.Makethereadingofgalvanometerbackto"0〃viamechanicalmethod・ii.OpenK,pressGbutton,adjustMandkeepthegalvanometerbalanee.iii.ConnectRxwithX.iv.Adjustthesystemandrecord

8、theresistanceRowhichmakethegalvanometerbalanee.Erroranalysis:Thelimitoffundamentalerroris:E

9、im=±a%(NR0+^)Theerrorcausedbythesensitivityofthebridgeboxis:AR^NRoyTherelativeuncertaintyofRxis:URx=jE《m+(AR。？1.Dataprocessing:TESTONE・Usesimplyconstru