【MOOC答案】《电磁场理论与微波工程》（北京理工大学）章节作业慕课答案

【答案】《电磁场理论与微波工程》（北京理工大学）章节作业慕课答案

有些题目顺序不一致，下载后按键盘ctrl+F进行搜索Chapter1VectorAnalysisChapter1Quiz11.单选题：Fordescriptionofthedivergenceinthevectorfield,whichofthefollowingstatementsiswrong？

选项：

A、Thedivergenceofvectorisascalar,whichisthefluxofthroughacertainpointperunitvolume.

B、Whenthedivergenceisequalto0,itmeansthatthereisnodivergencesourceatthatpoint.

C、Pointswithdivergencelessthan0emitvectorlines.

D、Avectorfieldwhosedivergenceis0everywhereiscalledadivergence-lessfield.

答案：【Pointswithdivergencelessthan0emitvectorlines.】2.单选题：Whichofthefollowingstatementsiscorrect?

选项：

A、

B、Stokes'theoremis

C、Inthepotentialfield,wehave

D、Thedivergencetheoremis

答案：【Stokes'theoremis】3.单选题：Insphericalcoordinatesystem,thevolumeelementdτcanberepresentedby

选项：

A、

B、

C、

D、

答案：【】4.单选题：Thedirectionalderivativeisequaltotheprojectionofthegradientvectorinthatdirection.

选项：

A、正确

B、错误

答案：【正确】5.单选题：InHelmholtz'stheorem,ifthevectorfieldhassinglevalueoneverypointintheinfinitespacewithitsderivativeiscontinuousinboundedregion,andthesourceisdistributedinafiniteregion,thenthevectorfieldisuniquelydeterminedbyitsdivergenceorcurl.

选项：

A、正确

B、错误

答案：【错误】Chapter2ElectrostaticFieldsChapter2Quiz21.单选题：Thechargewithitsdensityisuniformlydistributedonaconductorspherewithradiusofa,whereisaconstant.Thenthetotalchargeonthesphereis

选项：

A、0

B、

C、

D、

答案：【0】2.多选题：Whataretrueofthefollowingstatements?

选项：

A、Theelectricfieldintensityvectoratapointinspaceisnotperpendiculartotheequipotentialplanepassingthroughthispoint.

B、Theelectricfieldstrengthisdirectedfromthelowpotentialplanetothehighpotentialplane.

C、Thepotentialdifferencebetweentwopointsisindependentofthepositionofthepotentialreferencepoint.

D、Anelectricdipoleisasystemofchargescomposedofapairofpointchargeswiththesamechargequantitybutoppositepolarityseparatedbysomedistance.

答案：【Thepotentialdifferencebetweentwopointsisindependentofthepositionofthepotentialreferencepoint.;Anelectricdipoleisasystemofchargescomposedofapairofpointchargeswiththesamechargequantitybutoppositepolarityseparatedbysomedistance.】3.多选题：Thereisacylinderwithradiusofainheelectricfield,thepotentialsonbothinsideandoutsidethecylinderare:,whichofthefollowingstatementsiscorrect?

选项：

A、Thereisachargeonthesurfaceofthecylinder.

B、Thereisnochargeonthesurfaceofthecylinder.

C、Theelectricfieldintensityisat0ontheinterfaceofr=a.

D、Theelectricfieldoutsidethecylinderisdependentonrand.

答案：【Thereisachargeonthesurfaceofthecylinder.;Theelectricfieldoutsidethecylinderisdependentonrand.】4.多选题：Whichofthefollowingstatementsarewrong?

选项：

A、TheGausslaw’sintegralformis.

B、TheGausslaw’sdifferentialformis.

C、Thelooplaw’sdifferentialformis

D、Thelooplaw’sintegralformis.

答案：【TheGausslaw’sdifferentialformis.;Thelooplaw’sdifferentialformis】5.单选题：TheelectricfieldstrengthofeachpointonanarbitraryGaussiansurfaceintheelectricfieldisdeterminedbythechargesdistributedoutsidetheGaussiansurface.

选项：

A、正确

B、错误

答案：【错误】6.单选题：Thecurlofelectrostaticfieldinspaceis0everywhere,andthereisnovortexsourceinelectrostaticfield.

选项：

A、正确

B、错误

答案：【正确】7.单选题：Thetangentialcomponentoftheelectricfieldstrengthisdiscontinuousontheinterfacebetweentwodielectrics.

选项：

A、正确

B、错误

答案：【错误】Chapter3ElectrostaticFieldsChapter3Quiz31.单选题：Steadycurrentfieldinconductivemediumsatisfies().

选项：

A、

B、

C、

D、

答案：【】2.多选题：Theboundaryconditionofsteadycurrentfieldinconductivemediumis().

选项：

A、

B、

C、

D、

答案：【;】3.多选题：Inthefollowingexpressions,whicharecorrect?

选项：

A、Thedifferentialformofsteadycurrentcontinuityequationis.

B、ThedifferentialformofOhm'slawis.

C、ThepotentialforsteadycurrentfieldinahomogenousconductingmediumsatisfiesLaplace'sequation.

D、ThedifferentialformofJoule'slawis.

答案：【ThedifferentialformofOhm'slawis.;ThepotentialforsteadycurrentfieldinahomogenousconductingmediumsatisfiesLaplace'sequation.;ThedifferentialformofJoule'slawis.】4.单选题：Thenormalcomponentofthecurrentdensityisdiscontinuousontheinterfacebetweendifferentdielectrics.

选项：

A、正确

B、错误

答案：【错误】5.单选题：Thecurrentwhichisinvariantwithtimeiscalledsteadycurrent,andthecorrespondingelectricfieldissteadycurrentfield.

选项：

A、正确

B、错误

答案：【正确】Chapter4MagnetostaticFieldsChapter4Quiz41.单选题：In(),magnetizationphenomenonoccursundertheactionofexternal().

选项：

A、Magneticmedium,electricfield

B、Magneticmedium,magneticfield

C、Dielectric,magneticfield

D、Dielectric,electricfield

答案：【Magneticmedium,magneticfield】2.单选题：Inthemagneticmedium,istheintegralformofthe().

选项：

A、Lawofelectromagneticinduction

B、GaussTheorem

C、Ampere’slooptheorem

D、Currentcontinuityequation

答案：【Ampere’slooptheorem】3.多选题：Whichofthefollowingdescriptionarecorrect?

选项：

A、Whenfreecurrentsexistontheinterface,thetangentialcomponentofthemagneticfieldstrengthisdiscontinuousattheinterface.

B、Theclosedmagneticlinesatisfiestheleft-handedscrewrelationwiththecurrentintersectsit.

C、Theconstitutiverelationofamagnetostaticfieldinthemagneticmediumis.

D、Theintegralformofthemagneticfluxcontinuityequationis

答案：【Whenfreecurrentsexistontheinterface,thetangentialcomponentofthemagneticfieldstrengthisdiscontinuousattheinterface.;Theintegralformofthemagneticfluxcontinuityequationis】4.单选题：Thetangentdirectionofanarbitrarypointofthemagneticinductionlineisthedirectionofthemagneticfieldstrength

选项：

A、正确

B、错误

答案：【错误】5.单选题：Theelectricfieldmustbegeneratedbytheelectriccharge,andthemagneticfieldmustbegeneratedbytheelectriccurrent.

选项：

A、正确

B、错误

答案：【错误】Chapter5ElectromagneticInductionChapter5Quiz51.单选题：Asingle-turnloopwithanareaof0.1m2isplacedinthemagneticfieldwiththefrequencyof10MHzintheair.Iftheelectromotiveforceof1Vistobeinducedontheloop,theminimummagneticfieldstrengthHrequiredis()A/m?

选项：

A、0.1

B、0.111

C、0.125

D、0.126

答案：【0.126】2.单选题：Alongsolenoidwithradiusofisaistightlywindedbycoilofnturnsperunitlength.Ifthepermeabilityoftheironcoreisμ,theself-inductanceperunitlengthis().

选项：

A、

B、

C、

D、

答案：【】3.单选题：Alongsolenoidwithradiusofisaistightlywindedbycoilofnturnsperunitlength.IfthereisacurrentIinthecoil,findthemagneticfieldenergystoredperunitlength.(Supposethepermeabilityoftheironcoreisμ)

选项：

A、

B、

C、

D、

答案：【】4.单选题：Themagneticfieldvarieswithtime,buttheshapeandpositionoftheloopisstationary.Theelectromotiveforceonlygeneratedbythemagneticfluxchangeduetothetimevaryingmagneticfieldistheinducedelectromotiveforce.

选项：

A、正确

B、错误

答案：【正确】5.单选题：Lenz'slawstatesthatthemagneticfluxgeneratedbytheinducedcurrentalwaystriestocompensateforthechangeintheoriginalmagneticflux.

选项：

A、正确

B、错误

答案：【正确】Chapter6TimeVaryingElectromagneticFieldChapter6Quiz61.单选题：TheMaxwell'sequationsdescribeswhichofthefollowingrelation().

选项：

A、electrostaticandstaticmagneticfields

B、theinteractionofchangingelectricandmagneticfields

C、electrostaticandchangingmagneticfields

D、changingelectricandstaticmagneticfields

答案：【theinteractionofchangingelectricandmagneticfields】2.单选题：ThegeneralizedAmpere'sCircuitLawincludesthedisplacementcurrentconsidering().

选项：

A、thechangesinelectricfieldstrength

B、thechangesinmagneticfieldstrength

C、thechangesincurrentstrength

D、theequations’consistency

答案：【theequations’consistency】3.单选题：Inasinusoidalelectromagneticfield,electricandmagneticfieldshavewhichofthefollowingpropertiesregardingtheiramplitude().

选项：

A、theelectricfieldhasconstantamplitude.

B、themagneticfieldhasconstantamplitude.

C、theamplitudesoftheelectricandmagneticfieldsareproportionaltoeachother

D、theamplitudesoftheelectricandmagneticfieldsareindependentofeachother

答案：【theamplitudesoftheelectricandmagneticfieldsareproportionaltoeachother】4.单选题：Boundaryconditionsfortime-varyingelectromagneticfieldsapplyonlytothesurfaceofaconductor.

选项：

A、正确

B、错误

答案：【错误】5.单选题：Boundaryconditionsfortime-varyingelectromagneticfieldscanbeusedtodescribethereflectionofelectromagneticwaves.

选项：

A、正确

B、错误

答案：【正确】Chapter7PlaneWavesChapter7Quiz71.单选题：Thepolarizationdirectionofalinearlypolarizedwaveisdeterminedby().

选项：

A、theelectricfieldvectormovingdirection

B、themagneticfieldvectormovingdirection

C、thewavepropagationdirection

D、theanglebetweentheelectricandmagneticfieldvectors

答案：【theelectricfieldvectormovingdirection】2.单选题：Thewaveimpedanceofauniformplanewaveinanidealmediumisdependenton().

选项：

A、thefrequencyofthewave

B、theamplitudeofthewave

C、thepermittivityandpermeabilityofthemedium

D、thephasevelocityofthewave

答案：【thepermittivityandpermeabilityofthemedium】3.单选题：Whichisthewaveequationforauniformplanewaveinanidealmedium?

选项：

A、

B、

C、

D、

答案：【】4.单选题：Inanidealmedium,thewavelengthofauniformplanewavedependsonlyonthefrequencyofthewave.

选项：

A、正确

B、错误

答案：【错误】5.单选题：Whentheuniformplanewavepropagatesinanidealmedium,itswavelengthvarieswithpropagationdistance.

选项：

A、正确

B、错误

答案：【错误】Chapter8GuidedWavesChapter8Quiz81.单选题：Fortheelectromagneticwaveatafixed-frequency,thegroupvelocityofthisguidedwaveinaPECwaveguideisusually():

选项：

A、higherthanthephasevelocity

B、lowerthanthephasevelocity

C、equaltothephasevelocity

D、itcannotbedetermined

答案：【lowerthanthephasevelocity】2.单选题：Whichisthefundamentalmodeofarectangularwaveguide?

选项：

A、

B、

C、

D、

答案：【】3.单选题：InaPECwaveguide,whichofthefollowingfactorsaffectsthepropagationcharacteristicsofaguidedelectromagneticwave?

选项：

A、thewavelengthoftheelectromagneticwave

B、thefrequencyoftheelectromagneticwave

C、theshapeandsizeofthewaveguide’scross-section

D、theincidentangleoftheelectromagneticwave

答案：【theshapeandsizeofthewaveguide’scross-section】4.单选题：Thecutofffrequencyofallmodesinarectangularwaveguideisrelatedtotheheightandwidthofthewaveguide.

选项：

A、正确

B、错误

答案：【正确】5.单选题：Inarectangularwaveguide,thehigherordermodesexceptforthefundamentalmodecanbetransmittedinasinglemode.

选项：

A、正确

B、错误

答案：【错误】Chapter9RadiationofElectromagneticWaveChapter9Quiz91.单选题：Theradiationfieldofanelectricdipoleinthefar-fieldregionusuallybehaves()

选项：

A、inthesamedirectionasthedipoleaxis

B、perpendiculartothedipoleaxis

C、independentofthedipoleaxis

D、withanangleof45degreestothedipoleaxis

答案：【perpendiculartothedipoleaxis】2.单选题：TheHertziandipoleiscenteredattheorigin,itsfar-fieldexpressionhaswhichofthefollowingrelationwiththedistancefromobservationpointtooriginr?

选项：

A、thefieldisproportionalto1/r

B、thefieldisproportionalto1/r2

C、thefieldisproportionalto1/r3

D、hasnothingtodowithr

答案：【thefieldisproportionalto1/r】3.单选题：WhichofthefollowingisNOTantennaspecification?

选项：

A、radiationpattern

B、gain

C、efficiency

D、resistance

答案：【resistance】4.单选题：Thedualityofelectricityandmagnetismimpliestheelectricandmagneticfieldsbehavethesameinallcases.

选项：

A、正确

B、错误

答案：【错误】5.单选题：Theradiationpowerofanelectricdipoleisproportionaltoitsfrequency.

选项：

A、正确

B、错误

答案：【错误】Chapter10TransmissionLineTheoryChapter10Quiz101.单选题：Thetransmissionlinewithlengthof1mcarryinga900MHzsignalis().

选项：

A、Longlineandlumpedelementcircuit

B、Longlineanddistributedelementcircuit

C、Shortlineandlumpedelementcircuits

D、Shortlineanddistributedelementcircuits

答案：【Longlineanddistributedelementcircuit】2.多选题：Whichofthefollowingstatementarecorrect?

选项：

A、Electromagneticenergyistransmittedintwoways.Oneiscarriedbythecurrentintheconductorofthetransmissionline.Theotherispropagatedbythemediumaroundthetransmissionlineconductor.

B、Atransmissionlinewithl/λ>0.1isgenerallyconsideredasalongline

C、Therearethreeoperatingstatesonlosslesstransmissionlines:travelingwave,standingwaveandtravelingstandingwave

D、Transmissionpowerisequaltoreflectedpowerminusincidentpower

答案：【Electromagneticenergyistransmittedintwoways.Oneiscarriedbythecurrentintheconductorofthetransmissionline.Theotherispropagatedbythemediumaroundthetransmissionlineconductor.;Atransmissionlinewithl/λ>0.1isgenerallyconsideredasalongline;Therearethreeoperatingstatesonlosslesstransmissionlines:travelingwave,standingwaveandtravelingstandingwave】3.多选题：Whenanalyzingthetransmissionlinebydistributedelementequivalentcircuit,whichofthefollowingstatementarecorrect?

选项：

A、ThedistributedresistanceRisgeneratedduetothenon-idealoftheconductorsconstitutingthetransmissionline

B、ThedistributedconductanceGisgeneratedduetothenon-idealmediumbetweenthetwoconductorsofthetransmissionline

C、ThedistributedinductanceLisproducedbytheself-inductanceofthetransmissionline

D、ThedistributedcapacitanceCisproducedbythevoltagedropbetweenthetwowires

答案：【ThedistributedresistanceRisgeneratedduetothenon-idealoftheconductorsconstitutingthetransmissionline;ThedistributedconductanceGisgeneratedduetothenon-idealmediumbetweenthetwoconductorsofthetransmissionline;ThedistributedinductanceLisproducedbytheself-inductanceofthetransmissionline;ThedistributedcapacitanceCisproducedbythevoltagedropbetweenthetwowires】4.单选题：Forapurelyreactiveloadwithimpedanceof,thereflectioncoefficientmagnitudeisalwaysunity.AssumethatthecharacteristicimpedanceZ0isreal.

选项：

A、正确

B、错误

答案：【正确】5.单选题：Thekeydifferencebetweencircuittheoryandtransmissionlinetheoryistheelectricalsize.

选项：

A、正确

B、错误

答案：【正确】Chapter11MicrowaveNetworkAnalysisChapter11Quiz111.单选题：Amongbelowstatementsregardingtheimpedance,whichisINCORRECT?

选项：

A、ηrepresentstheintrinsicimpedanceofamedium.Thisimpedanceisonlydependentonthematerialparametersofthemedium,andisequaltothewaveimpedanceoftheplanewave.

B、Zωstandsforthewaveimpedance.Theimpedanceisacharacteristicofaparticularwavetype.TEM,TMandTEwaveshavedifferentwaveimpedancesdependingonthetypeoftransmissionlineandwaveguide,materialproperties,andoperatingfrequency.

C、Z0representsthecharacteristicimpedance.Thecharacteristicimpedanceistheratioofthetravelingwavevoltagetothecurrentonthetransmissionline.TherearenouniquelydefinedvoltagesandcurrentsforTEM,TE,andTMwaves.

D、Similarasthepropertiesofplaneelectromagneticwave,theimpedanceoftransmissionlineisdependentonthepropagationdirection.Inthisway,impedancecanbeconsideredasthelinkbetweenfieldtheoryandtransmissionline/circuittheory.

答案：【Z0representsthecharacteristicimpedance.Thecharacteristicimpedanceistheratioofthetravelingwavevoltagetothecurrentonthetransmissionline.TherearenouniquelydefinedvoltagesandcurrentsforTEM,TE,andTMwaves.】2.多选题：Acomplexmicrowavenetworkconsistsofmanysimplemicrowavenetworkswhichareclassifiedindifferentways.Whichofthefollowingstatementarecorrect?

选项：

A、Accordingtothenumberoftransmissionlineportsconnectedtoit,themicrowavenetworkcanbedividedintooneport,twoports,andmulti-portnetwork.

B、Accordingtothepropertiesofthecircuitcomponents,themicrowavenetworkcanbedividedintoactiveandpassivenetworks,linearandnonlinearnetworks,andreversibleandnon-reversiblemicrowavenetworks.

C、Thepowerdividerandferritey-shapedcirculatorbelongtothefour-portnetwork.Andthehybridconnectors,directionalcouplers,anddirectionalfiltersbelongtothethree-portnetwork.

D、Examplesoftwo-portnetworkincludemicrowavefilters,modeconverters(usedtotransformoneelectromagneticwavemodeinthewaveguidetoanother),polarizationconverters(usedtochangethepolarizationpropertiesofelectromagneticwavesinthewaveguide),phaseshifters,ferritesandisolators.

答案：【Accordingtothenumberoftransmissionlineportsconnectedtoit,themicrowavenetworkcanbedividedintooneport,twoports,andmulti-portnetwork.;Accordingtothepropertiesofthecircuitcomponents,themicrowavenetworkcanbedividedintoactiveandpassivenetworks,linearandnonlinearnetworks,andreversibleandnon-reversiblemicrowavenetworks.;Examplesoftwo-portnetworkincludemicrowavefilters,modeconverters(usedtotransformoneelectromagneticwavemodeinthewaveguidetoanother),polarizationconverters(usedtochangethepolarizationpropertiesofelectromagneticwavesinthewaveguide),phaseshifters,ferritesandisolators.】3.多选题：Whichofthefollowingstatementarecorrect？

选项：

A、Therearemultiplewaystodefinetheequivalentvoltage,currentandimpedanceofthewaveguide,asthesequantitiesarenotuniquefornon-TEMlines

B、Whenthevoltageandcurrentaredefinedforaspecificwaveguidemode,thevoltagedefinedisproportionaltothetransverseelectricfield,andthecurrentdefinedisproportionaltothetransversemagneticfield.

C、Thesameasthevoltageandcurrentinthecircuittheory,theproductofthoseequivalentvoltageandcurrentinthetransmissionlinetheoryshouldbedeterminedasthepowerflow.

D、Thevoltagetocurrentratioofasingletravelingwaveshouldbeequaltothecharacteristicimpedanceofthetransmissionline.Theimpedanceisarbitraryinchoice,butitisusuallychosentobeequaltothewaveimpedanceofthetransmissionlineornormalizedto1.

答案：【Therearemultiplewaystodefinetheequivalentvoltage,currentandimpedanceofthewaveguide,asthesequantitiesarenotuniquefornon-TEMlines;Whenthevoltageandcurrentaredefinedforaspecificwaveguidemode,thevoltagedefinedisproportionaltothetransverseelectricfield,andthecurrentdefinedisproportionaltothetransversemagneticfield.;Thesameasthevoltageandcurrentinthecircuittheory,theproductofthoseequivalentvoltageandcurrentinthetransmissionlinetheoryshouldbedeterminedasthepowerflow.;Thevoltagetocurrentratioofasingletravelingwaveshouldbeequaltothecharacteristicimpedanceofthetransmissionline.Theimpedanceisarbitraryinchoice,butitisusuallychosentobeequaltothewaveimpedanceofthetransmissionlineornormalizedto1.】4.单选题：Themicrowavenetworkreferstoanareaofarbitraryshapeandstructurewithanumberofoutputandinputportswhichisafunctionalmicrowavecircuitorsystemcomposedofmicrowavecomponentsconnectedbywaveguidesortransmissionlines.

选项：

A、正确

B、错误

答案：【正确】5.单选题：Microwaveelementslikedirectionalcouplersandphaseshiftersareequivalenttolossymicrowavenetworks,whilemicrowaveelementslikematchingloadsandattenuatorsareequivalenttolossymicrowavenetworks.

选项：

A、正确

B、错误

答案：【错误】Chapter12ImpedanceMatchingandTuningChapter12Quiz121.单选题：WhichofthefollowingmethodsCANNOTbeusedforimpedancematching?

选项：

A、λ/4impedanceconverter

B、Singlestub

C、lumpedelements

D、filter

答案：【filter】2.单选题：Inordertoachievemaximumoutputpowerdeliveredfromthesignalsource,itisrequiredthattheinternalimpedanceofthesignalsourceandtheinputimpedanceatthestartingpointofthetransmissionlinehaswhichofthefollowingrelation.().

选项：

A、theyarewiththeoppositepolarity

B、theyareconjugatecomplexnumbers

C、thelatteristheabsolutevalueoftheformer

D、theyarereciprocal

答案：【theyareconjugatecomplexnumbers】3.单选题：thepurposeofmakingtheloadresistanceequaltothecharacteristicresistanceofthetransmissionlineis()?

选项：

A、sothattheloadabsorbsalltheincidentpowerwithoutanyreflectingwaves

B、sothatloadwillreflectallthewaves

C、sothattheloadcanreflecttheelectromagneticwaves

D、sothattheloaddoesnothavetheheatloss

答案：【sothattheloadabsorbsalltheincidentpowerwithoutanyreflectingwaves】4.单选题：Thematchingnetworkisideallylossless.Soitisusuallydesignedwiththeimpedanceseenlookingintothematchingnetworkis1/Z0.

选项：

A、正确

B、错误

答案：【正确】5.单选题：Whenadoptingaλ/4impedancetransformerinmatching,weshouldconnectittothemaintransmissionlineatthelocationwheretheinputimpedanceispurelyresistiveseenlookingtowardstheload.

选项：

A、正确

B、错误

答案：【正确】Chapter13MicrowaveComponentsChapter13Quiz131.单选题：WhichoffollowingisNOTtraditionalmicrowavecomponents?

选项：

A、E-andH-planewaveguideT-junction

B、Waveplate

C、MagicT

D、Thecouplersusingcoaxialprobes

答案：【Waveplate】2.多选题：Thecharacteristicso