M29_KNIG7655_03_ITG_CH29

《M29_KNIG7655_03_ITG_CH29》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。

1、CHAPTER29PotentialandFieldRecommendedclassdays:2minimum,3preferredBackgroundInformationTheprimarydifficultiesthatstudentshavewiththeconceptofpotentialwerediscussedinthelastchapter.Inparticular,d•Studentshaveaveryhardtimeunderstandingtherelationshipbetween

2、EandV.Standardnumericalproblemsusingtheelectricpotentialdolittletobuildaconceptualunderstandingofwhatpotentialisallabout.Studentsneedampleopportunitiestoworkwithgraphs,potentialmaps,andequipotentialsurfacesiftheyaretounderstandthelinksbetweenfieldandpoten

3、tial.•Studentsviewbatteriesasconstantcurrentsourcesratherthanassourcesofpotentialdifference.Tochangethismisconceptionrequiresbothexperimentalevidenceandamentalmodelofwhatabatterydoes.Chapter28introducedtheconceptofpotential,andthischapterwillnowtrytomaket

4、heideamore“real”bylinkingitbothtocharges/fieldsandtobatteries.StudentLearningObjectivesd•ToestablishtherelationshipbetweenEandV.•Tolearnmoreaboutthepropertiesofaconductorinelectrostaticequilibrium.•Tointroducebatteriesasapracticalsourceofpotentialdifferen

5、ce.•Tofindtheconnectionbetweenchargeandpotentialdifferenceforacapacitor.•Toanalyzesimplecapacitorcircuits.29-1PedagogicalApproachAsdescribedinthelastchapter,theconceptoftheelectricpotentialisverydifficultformoststudentstograsp.Todealwiththis,classtimeshou

6、ldfocusonreasoning,qualitativeunderstanding,andlinkingpotentialtomoretangiblequantitiessuchascurrents,charges,andfields.Thecomputationaldemandsofthischapterarenothard,andstudentsshouldhavelittledifficultywiththenumericalaspectsofproblemsolvingiftheyunders

7、tandhowtheconceptsareused.dAnimportanttaskistoestablishtherelationshipbetweenEandV.Studentsneedhelpandpracticewith:•Readingtwo-dimensionalandthree-dimensionalgraphsandmapsofthepotential.Theanalogywithtopographicmapsishelpful,butasurprisingnumberofstudents

8、arenotfamiliarwithandcannotreadatopographicmap.•Understandingequipotentiallinesandsurfaces.d•RecognizingthatEpoints“downhill”onacontourmapandthatthefieldstrengthEistheslopeofthe“potentialhill.”d•RecognizingthatEisal