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1、CURRENTS&CHARGECONTINUITYClassActivities:current(1)ClassActivities:Current(2)CurrentthroughaWireAstudentarguesthatthecurrentthroughawireflowsthroughoutitsvolume,you:Agree,resistanceisinverselyproportionaltocrosssectionalarea,notcircumferenceDisagree,itmustflowonlyonthesurfaceofthewireb

2、ecausethenegativechargesrepeleachotherAgreefordifferentreasonsDisagreefordifferentreasonsPositiveionsflowrightthroughaliquid,negativeionsflowleft.Thespatialdensityandspeedofbothionstypesareidentical.Isthereanetcurrentthroughtheliquid?Yes,totherightB)Yes,totheleftC)NoD)Notenoughinforma

3、tiongiven5.5A)B)C)D)E)NoneoftheaboveCurrentIflowsdownawire(lengthL)withasquarecrosssection(sidea)Ifitisuniformlydistributedovertheentirewirearea,whatisthemagnitudeofthevolumecurrentdensityJ?5.7A)B)C)D)E)NoneoftheaboveCurrentIflowsdownawire(lengthL)withasquarecrosssection(sidea)Ifitis

4、uniformlydistributedovertheoutersurfacesonly,whatisthemagnitudeofthesurfacecurrentdensityK?5.6A"ribbon"(widtha)ofsurfacecurrentflows(withsurfacecurrentdensityK)Rightnexttoitisasecondidenticalribbonofcurrent.Viewedcollectively,whatisthenewtotalsurfacecurrentdensity?Ka5.8A"ribbon"(width

5、a)ofsurfacecurrentflows(withsurfacecurrentdensityK)Rightnexttoitisasecondidenticalribbonofcurrent.Viewedcollectively,whatisthenewtotalsurfacecurrentdensity?A)KB)2KC)K/2D)Somethingelsea5.8A"ribbon"(widtha)withuniformsurfacecurrentdensityKpassesthroughauniformmagneticfieldBext.Onlyth

6、elengthbalongtheribbonisinthefield.Whatisthemagnitudeoftheforceontheribbon?KBaKBabKBbKB/aKB/(ab)ERK5-1abBextKChargeConservationWhichofthefollowingisastatementofchargeconservation?A)B)C)D)E)Notsure/can'tremember5.10Untilnow,youhavebeentoldthatmagneticfieldslooparoundacurrentcarryingwire

7、.Buthowdoyouknowthattherearenoothercomponents?Show(mathematically)whichofthebelowB-fieldcomponentsare/notpossible.Isthetotalnetchargeintheuniverseconserved?Howaboutthetotalmass?Chargeisconserved;totalmassisconservedChargeisconserved;totalmassisnotconservedChargeisnotconserved;totalma