电磁场与电磁波作业答案

《电磁场与电磁波作业答案》由会员上传分享，免费在线阅读，更多相关内容在工程资料-天天文库。

1、Homework♦1.[Problem4.7]AsectionofcopperringisshowninFigureP4.7・FindtheresistancebetweentheboundariesAandB.FigureP4.7Solution:assume:Solutv?fen0=0，0=0when0=彳’0=Uthen:——-=0,/.0=C、(p+C2,Cj—,C,=0dqrn-1口丹右602aUJ=aE=-av(p=-aa=-a2aUt1bIn—7ia®rd(ppnr7ir*2.[Problem4.8]Atruncatedcircularcone,asillustrate

2、dinFigureP4.8,ismadeofiron.Whatistheresistanceoftheconebetweenitsflatends?Solution:SolutAmdz、2r2-rr+———zJI)/、Ar2-r.Tdr+———Lz、2Ii丿6T石一斤J。—I6T（右一勺）=5.3x10—6(0)

3、ofthesamematerialandhavethesamelengthandresistance,whatmustbetheouterradiusofthehollowconductor?Solution:7i{r^-r)=♦4.[Problem4.10]Acopperwireofarealcm2carriesauniformlydistributedcurrentof200A.Iftheelectrondensityincopperis8.5X1028electronspercubicmeter;determinetheaveragedriftvelocityoftheelec

4、trons.Whatistheelectricfieldintensityinthewire?Ifthewireis100kmlong,calculatethepotentialdifferencebetweenitsends・Whatistheresistanceofthewire?Solution:a.l=—pSevSolution:u—O/1.47X10"4(mJs)—200。/v=叫8.5xlO28IO-41.6IO'19J=aE200"，5・80xIO：ICT4^3.45xl0-2(V/m)U=E1=3A5(kV)LaS=17.24(G)