2015年电大电工电子技术试题（三）期末复习考试资料

电工电子技术模拟题（三）一、填空题每空2分，共20分1稳压二极管有一个相对普通二极管较低的反向击穿电压。在特性曲线上，其反向击穿特性曲线很陡，击穿后在安全的工作电流范围内，能够保证电压变化很小。2运放电路时常用到的三项理想化指标是开环差模电压放大倍数AOD为（无穷大）；差模输入电阻RID（无穷大）；差模输出电阻ROD为（零）。3组合逻辑电路的特点是从逻辑功能上看（输出）只与（当时）输入的逻辑值有关，而与该时刻之前的输入及电路状态均（无关）。4D触发器具有（置位）、（复位）两种功能二、单项选择题（每题4分，共20分）1、图1所示电路中，电流表正负接线端用“”、“”号标出。今电流表指针正向偏转，示数10A，有关电流、电压方向也表示在图中，则（C）正确。AI110A，U6VBI110A，U6VCI110A，U12V2、图2所示电路中，判断电阻R中流通的电流及消耗的功率为（B）。A0A，2WB1A，2WC1A，4W3、在正弦交流纯电容电路中，电压与电流的关系是（C）。AIBICIUCUCU4、已知电路某元件的电压U和电流I分别为U141COS（314T600）V，I7SIN（314T1200）A，则该元件的性质是（A）。A电容B电感C电阻5、在三相电路中，三相对称负载为星形连接，三个线电流均为4A，则中线电流为（C）。A4AB12AC0AA20V324V31063I1U图11A22VR图2三、计算题（每题15分，共30分）1、用戴维南定理求图31电路中R5所在支路的电流。已知R1R2R4R55，R310，U65V。解断开R5，求开路电压UO和入端电阻R0UBDU433V31UCDU325V42RUBCUBDUDCUBDUCD108V将U短路R0（R1/R3）（R2/R4）583求出电流I5为I501A5050UBC2、一台三相异步电动机，磁极对数P2，工作额定电压为380V，额定频率为50HZ，已知额定转速为1450R/MIN，求其同步转速和额定转差率解1）同步转速N11500R/MINPF60252）额定转差率SN00331N045四、简答题（每题5分，共30分）1、负载增加的涵义是什么在近似恒压源供电或近似恒流源供电系统中，负载增加相当于负载DCBAR5R4R3R2R1U图31电阻增大还是减小负载增加意指电路的输出功率增加。在近似恒压源供电系统中，负载获得的功率PUI，负RU2载增加既是负载电流增大，相当于负载电阻减小。在近似恒流源供电的系统中，负载获得的功率PUII2R，负载增加既是负载电压增大，相当于负载电阻加大。2、在电路分析与计算中，戴维南定理最适宜应用于哪种情况如果只需计算电路中某一支路的电流，此时最适宜采用戴维南定理。3、三相交流电路中，负载星形连接时，相电流与线电流，相电压与线电压有何关系相电流与线电流的关系为IPIL相电压与线电压的关系为ULUP34、三相异步电动机的调速方式主要有哪几种有三种（1）改变电源频率调速；（2）改变转差率的调速；（3）异步电动机变极调速。5、接触器分为哪两类接触器的功能是什么主要用于哪些地方接触器是一种自动电器，有直流接触器和交流接触器之分，其功能是可以频繁的接通或断开交、直流电路及大容量控制电路。主要用于控制电动机、电热设备、电焊机等，尤其在电力拖动系统中应用广泛。6边沿型JK触发器，在CP脉冲信号的作用下，其动作有何特点（分为负边沿、正边沿两种情形）答负边沿型（下降沿触发型）CP下降沿到来的前一刻瞬间，J、K接收输入；CP下降沿到来后产生输出。正边沿型（上升沿触发型）CP上升沿到来前一刻瞬间，J、K接收输入；CP上升沿到来后产生输出。请您删除一下内容，O_O谢谢2015年中央电大期末复习考试小抄大全，电大期末考试必备小抄，电大考试必过小抄AFTEREARNINGHISSPURSINTHEKITCHENSOFTHEWESTIN,THESHERATON,SENSONTHEBUND,ANDASPRINKLINGOFOTHERTOPNOTCHVENUES,SIMPSONLUFINALLYGOTTHECHANCETOBECOMEHISOWNBOSSINNOVEMBER2010SORTOFTHESHANGHAIBORNCHEFMIGHTNOTACTUALLYOWNCALIFORNIAPIZZAKITCHENCPKBUTHEISINSOLECHARGEOFBOTHKITCHENANDFRONTOFHOUSEATTHISSINANMANSIONSSTALWART“ITSCERTAINLYARESPONSIBILITYTOBETHEHEADCHEF,ANDTHENTOHAVETOMANAGETHERESTOFTHERESTAURANTASWELL,“THE31YEAROLDTELLSENJOYSHANGHAI“INHOTELS,FOREXAMPLE,THESEJOBSARESTRICTLYDEMARCATED,SOITSAGREATOPPORTUNITYTOLEARNHOWABUSINESSOPERATESACROSSTHEBOARD“ITWASATASKTHATMANAGEMENTBACKINSUNNYCALIFORNIAEVIDENTLYFELTHEWASREADYFOR,ANDAVOTEOFCONFIDENCEFROMACOMPANYTHAT,TODATE,HASOPENED250OUTLETSIN11COUNTRIESANDFORADDEDPRESSURE,THESHANGHAIBRANCHWASALSOCPKSCHINADEBUT“FORSUREITWASABIGSTEP,ANDUNLIKEALLTHEIROTHERASIAOPERATIONSTHATAREFRANCHISES,THEYDECIDEDTOMANAGEITDIRECTLYTOBEGINWITH,“SAYSSIMPSONTWOYEARSAGOAPRIVATEFRANCHISEETOOKOVERTHELEASE,BUTTHELINKSTOCPKHEADQUARTERSARESTILLSTRONG,WITHAMAINLANDBASEDBRANDAMBASSADORONHANDTOENSURETHEBUSINESSADHERESTOITSETHOSOFCREATING“INNOVATIVE,HEARTHBAKEDPIZZAS“,ASLICEOFPRBLURBTHATSIMPSONINSISTSLIVESUPTOTHEHYPE“THEYAREVERYINNOVATIVE,“HESAYS“THEPROBLEMWITHMOSTFASTFOODPLACESISTHATTHEYUSETHESAMESAUCEONEVERYPIZZAANDJUSTCHANGETHETOPPINGSEVERYONEOFOUR16PIZZASAUCESISAUNIQUERECIPETHATHASBEENFORMULATEDTOCOMPLEMENTTHETOPPINGSPERFECTLY“THELARGELYLOCALCUSTOMERBASEEVIDENTLYAGREESANDONSATURDAYANDSUNDAY,ATLEAST,THEPLACEISTEEMINGTHEKIDSEATFORFREEPOLICYATWEEKENDSISUNDOUBTEDLYABIGDRAW,ASWELLASISTHESPACIOUSSECONDFLOORLAYOUTOVERLOOKEDBYACANOPYOFGREENFROMFUXINGPARKOVERTHEROADTHECOMPANYISALSOFOCUSINGONINCREASINGBRANDRECOGNITIONANDINRECENTYEARSHASTAKENPARTINOUTSIDEEVENTSSUCHASTHEREGULARCALIFORNIAWEEKSTILL,THESTAAREHONESTENOUGHTOADMITTHATBUSINESSCOULDBEBETTERASGOOD,INFACT,ASINCPKSSECONDOUTLETINTHEPOPULARKERRYPARKSIDESHOPPINGMALLINPUDONG“SINANMANSIONSHASREALLYSTRUGGLEDTOGETTHENUMBEROFVISITORSTHATWEREENVISAGEDWHENITFIRSTOPENED,ANDITHASNTBEENEASYFORANYOFTHETENANTSHERE,“ADDSSIMPSON“WEREPLANNINGATHIRDOUTLETINTHECITYIN2015,ANDWEWILLPROBABLYCHOOSEASHOPPINGMALLAGAINBECAUSEOFTHEBETTERFOOTTRAFFIC“THETEAROOMSONCEFREQUENTEDBYCOCOCHANELANDMARCELPROUSTAREUPPINGSTICKSANDCOMINGTOSHANGHAI,XUJUNQIANVISITSTHEPARISIANOUTPOSTWITHSWEETTREATSONETHINGTHECENTURYOLDPARISIANTEAROOMANGELINAHASSHOWNISTHATLEGENDARYFASHIONDESIGNERCOCOCHANELNOTONLYHADSTYLEANDGLAMORBUTALSOBOASTEDGREATTASTEINFOOD,PASTRIESINPARTICULARONEOFTHEMOSTPOPULARTEAROOMSINPARIS,ANGELINAISFAMOUSFORHAVINGONCEBEENFREQUENTEDBYCELEBRITIESSUCHASCHANELANDWRITERMARCELPROUSTNOWANGELINAHASPACKEDUPITSFRENCHAMBIENCE,EFFICIENTSERVICE,ANDBEAUTIFUL,COMFORTINGDESSERTSANDFLOWNTHEMTOSHANGHAIATTHEFLAGSHIPDINEINANDTAKEOUTSPACEINSHANGHAI,EVERYTHINGMIMICSTHEORIGINALTEAROOMDESIGNEDFROMTHEBEGINNINGOFTHE20THCENTURY,INPARIS,THEHEIGHTOF“BELLEEPOQUE“THEPAINTINGSONTHEWALL,FOREXAMPLE,AREEXACTLYTHESAMEASTHEONETHATDEPICTSTHELANDSCAPEOFSOUTHERNFRANCE,THEHOMETOWNOFTHEOWNERANDTHESMALLTABLESAREINTENTIONALIMITATIONSOFTHEONESTHATCOCOCHANELONCESATATEVERYAFTERNOONFORHOTCHOCOLATETHEFAMOUSHOTCHOCOLATE,KNOWNASLAFRICAIN,ISALUXURIOUSMIXTUREOFFOURTYPESOFCOCOABEANSIMPORTEDFROMAFRICA,BLENDEDINPARISANDTHENSHIPPEDTOSHANGHAIITSSINFULLYSWEET,RICHANDTHICKASIFPUTTINGABAROFMELTINGCHOCOLATEDIRECTLYONTHETONGUEANDTHEFRESHWHIPPEDCREAMONTHESIDEMAKESALIGHT,BUTEQUALLYGRATIFYINGCONTRASTITISALSOSOLDINGLASSBOTTLESASTAKEAWAYTHESIGNATUREMONTBLANCCHESTNUTCAKECONSISTSOFTHREEPARTSTHEPUREEDCHESTNUTONTOP,THEVANI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