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1、热工仪表初选择（Initialselectionofthermalinstrument）Multiple-choicequestions1.Whentheelectricfieldisusedtodescribetheelectricfield,theelectricfieldoftheuniformelectricfieldis().Aandperpendiculartoeachother;Bandparalleltoeachother;Candpowerlinesintersect.Answer:B.2.Thecurrentflowingintotheconductoratthesam
2、etimeisequaltothecurrentflowingoutoftheconductor.Thisprincipleiscalled()principle.A,currentequivalence,B,currentinvariance,C,continuityofcurrent.Answer:C.3,theelectricfieldforcestheelectricchargefrom()toformcurrent.A,lowpotentialshifttohighpotential;B,highpotentialshifttolowpotential;C,translation
3、distance.Answer:A.4,intheoutercircuit,theelectricforceforcesthepositivechargefromthepath(from)toformthecurrent.A,lowpotentialshiftedtohighpotential;B,highpotentialshiftedtolowpotential;Cshiftedadistance.Answer:B.5,intheload,thedirectionofthecurrentandthedirectionofthevoltageisalways().A,opposite;B
4、,consistent;C,arbitrary.Answer:B.6,inthepowersupply,thedirectionofthecurrentandvoltageis().A,consistent;B,opposite;C,same.Answer:B.7,PtypesemiconductorsandNtypesemiconductorsallhavecarriers,butthesemiconductordevicesthemselvesare().A,uncharged;B,positivelycharged;C,negativelycharged.Answer:A.8,the
5、intrinsicsemiconductorsgeneratecarriersduetothermalmotion,leadingtothepresenceof()intheintrinsicsemiconductorsA,electroncarriers,B,holecarriers,C,electroncarriersandholecarriers.Answer:C.9,Ptypesemiconductorischaracterizedby()TheconcentrationofAandfreeelectronsisgreaterthantheconcentrationofholes;
6、theconcentrationofBandholesisgreaterthantheconcentrationoffreeelectrons;theconcentrationofCandfreeelectronsisequaltotheconcentrationofholes.Answer:B.10.Accordingtotheminorerrorcriterion,themeasurementdataisusuallyadjustedaccordingtothe(allowed)errorofthemeasurement.A,0.05;B,0.1;C,0.5.Answer:B.11,t
7、heknowntruevalueis200degreescentigrade,themeasurementresultis202degreescentigrade,andtheabsoluteerroris().A,2,B,-2,C,2.Answer:A.12.Thestandardofmeasuringinstrumentsisusuallycalledqualityindex.A,performance;B,qual
