WhatisaFieldUBCPhysicsamp;AstronomyOutreachHome大學(xué)物理和天文學(xué)是一場宣傳家;課件

Legend-WhitebackgroundisforTeachertoseeasinstructions.-BluebackgroundisfortheStudenttosee

Legend-Whitebackgroundisfor1Mypresentationismoregeartowardupperlevelhighschoolphysicsstudent(i.e.Physics11,Physics12andPhysics12AP).Mypresentationismoregeart2MaterialsneededforthedemonstrationsMaterialsneededfortheconstructionofthedemosPliersSandpaperGluegun#1CathoderaytubedemoCathoderaytubeset#2Batterydemo9Vbatterythincopperwiresrubberbandaneodymiummagnet(orderonlinegrand-illusions/toyshoporebay)#3Ferromagneticlevitationborrowalevitationdevicefromayear2

MechanicalEngineering2019friend#4Diamagneticlevitation4neodymiummagnetsapieceofpyrolyticcarbon

Materialsneededforthedemos.Instructionswillbegiveninlaterslides#5MaglevtrainStrongmagneticstripsthinplexiglassthesupporttrackMaterialsneededforthedemon3ElectromagnetismUniversityofBritishColumbiaPhysics420By:JasonCheungElectromagnetismUniversityof4WhatisaField?AregionofspacecharacterizedbyaphysicalpropertyhavingadeterminablevalueateverypointintheregionExamples:gravitationalfield,Electricfield,andmagneticfieldWhatisaField?Aregionofsp5ExplanationofField(#1)

(forslide5)Thismeansifweputanythingappropriateinafield,wecanthencalculate“something”outofthatfieldBeforegoingfurtherwithElectricfieldandMagneticfield,mentiontherearesomethingcalledtheElectricandMagneticfield.Usegravitationalfieldasastart,becauseG-fieldthemosteasytounderstandLinkElectricfieldandMagneticfieldafterexplainingtheGravitationalfieldExplanationofField(#1)

(fo6GravitationalFieldDefinedasA=accelerationG=gravitationalconstantm=massofbigobjectr=distancetothecenterofthebigobjectGravitationalFieldDefinedas7WhatisaFieldUBCPhysicsamp;AstronomyOutreachHome大學(xué)物理和天文學(xué)是一場宣傳家;課件8ExplanationofField(#2)

(forslide8)IfweputBobinthegravitationalfield,wecancalculatetheForceactingonhimbytheEarth.HewillfollowthegravitationalfieldlinesandfalltothesurfaceoftheEarth.Essentially,ifweputanythingthathasamassintheGravitationalfield,wecancalculatethat“something”Imentionedbefore.That“something”isthe“gravitationalforce”inthiscase.Emphasizethatwedeterminedifferentkindsofforcewithdifferentkindsoffield.ThiscanbridgetoElectricandMagneticFieldonfollowingslides.ExplanationofField(#2)

(for9ElectricFieldElectricfieldisdefinedastheelectricforceperunitChargeItisthesurroundingchargesthatcreateanelectricfieldE=ElectricFieldF=ElectricForceq=ChargeEismeasureinForce/CoulombElectricFieldElectricfieldi10ExplanationofElectricField(E-field)(forslide10)#0 Explainwhatisacharge,q -TheyshouldhaveenoughPhysicstoknowwhatisa+/-chargeis -OppositechargesattracteachotherandLikechargesrepeleachother#1 ExplainEisdefinedasF/q -Ifweputa+/-(positiveornegative)chargeinaelectricfield,the+/-chargewill experienceaforce.Thisforceiscalled“ElectricForce” -(IMPORTANT!!)RecallfromG-field.G-fieldrequiresanobjectwithaMASStohavea force.E-fieldrequiresa+/-chargetohaveaforce#2 HowdoyoudrawtheE-fieldlineswithdifferentcharges? -Electricfieldlinesalwayscomesoutofthepositivechargeintothenegative charge -NegativechargealwaysabsorbtheE-fieldlines

ExplanationofElectricField11ExplanationofElectricField(E-field)(forslide10)#3 Whatdirectionistheelectricforce? -ThedirectionoftheElectricforceisparalleltotheelectricfield. -LookatthePOINTPonthediagramonslide10.Thearrowinthediagramrepresents thedirectionoftheelectricforce Q: Whatisthecharge,positiveornegative,ifthedirectionofthe forceispointingoutwardlikeinthediagramonslide10 A: Positivebecauseitispointawayfromthestationarypositive charge Q: Whatisthecharge,ifthedirectionoftheforceonthediagram switched?? A: NegativechargeExplanationofElectricField12WhatisaFieldUBCPhysicsamp;AstronomyOutreachHome大學(xué)物理和天文學(xué)是一場宣傳家;課件13CathodeRayTubeDemo(CRT)InstructionandexplanationfortheCRTDemo#1 TurnonthePowersupplyandElectricplatecontroller,andwaitandcalibratetheelectronstothe centerofthescreen#2 AdjusttheelectricplatebyturningtheXknobortheYknob.Thisistodemonstratethatthe electricplatecancontrolwheretheelectronwillhitonthescreen.QuestionsandFunfactsQ: WhatdoyouthinkistheapplicationofaCRTandwhatdotheelectricplatesdointheCRT?A: Our“OLD”TV(beforeLCDandPlasma)usethistechniquetoviewimagesonourTV!CathodeRayTubeDemo(CRT)Ins14MagneticFieldMagneticfieldisafieldthatexertsaforceonamovingchargeAmagneticfieldcanbecausedeitherbyanothermovingchargeorbyachangingofelectricfieldormagneticdipolesofmaterialsMagneticFieldMagneticfieldi15ExplanationofMagneticfield

(forslide15)Inordertohaveamagneticforce,weneedamoving+/-charge.MagneticfieldlinescomeoutofNandgointoS(seediagramonslide15)Emphasizethe3componentstoproduceamagneticfield #1Moving+/-charge #2ChangingofE-field #3Dipoleofmaterial(seediagramtoexplain)

ExplanationofMagneticfield

16MagneticFieldismeasureinTeslaAsimpleformulatocalculateMagneticFieldB= magneticfieldF= MagneticForceQ= chargeV= velocityofthemovingchargeMagneticFieldismeasureinT17ExplanationofMagneticfieldcon’t

(forslide15)TheunitofTeslaisaverySMALLunit -Earthmagneticfieldhasaround10^(-5)Tesla -AverygoodFerromagnethasaround0.5to1TeslaItisveryhardtomakematerialthathasaverystrongmagneticfield,andIwillexplainitinmoredetaillaterSinceIamdoingaqualitativestudyonmagnetism,Ijustgavethemoneofthemostbasicequationformagneticforce -EmphasizeontheCROSSPRODUCT,itisnottreatedasatimesoperator.Velocityofa +/-chargeneedstobe90degreetothemagneticfieldinordertohaveamagneticforceExplanationofMagneticfield18ConstructionofBatterydemoMaterialneededcopperloop9Vbatteryrubberbandcopperearsx2Stepone:pinchthecooperearsontothebatterySteptwo:tietheearsontothebatterywithrubberbandStepthree:putthecopperloopthroughtheholesonthecopperearsFinishproductCopperears9VbatteryRubberbandCopperloopConstructionofBatterydemoMa19VideoofbatterydemoShowBatteryDemovideounder“Videos”VideoofbatterydemoShowBatt20BatteryDemoInstructionofhowtousethebatterydemo #1Setupdeviceasabove #2Bringtheneodymiummagnetclosetotheloop #3GiveakickstartfortheloopbyflickingitThingstotellthestudents -Withoutthemagneticfield,theloopwillnomove -ItisduetotorqueprovidedbythemagneticforcesothattheloopwillgoroundandroundBatteryDemoInstructionofhow21ExtrainterestingtopicforthebatterydemoQ:Whatisgoingonwiththebattery?Answer:Thepermanentmagnetsexertforcesontheelectricalcurrentsflowingthroughtheloopofwire.Whentheloopofwireisinaverticalplane,theforcesonthetopandbottomwiresoftheloopwillbeinoppositedirections.Theseoppositelydirectedforcesproduceatwistingforce,ortorque,ontheloopofwirethatwillmakeitturn.Whyisitsoimportanttosandhalfofoneprojectingwire?Supposethatthepermanentmagnetsaremountedwiththeirnorthpolesfacingupward.Thenorthpoleofthepermanentmagnetwillrepelthenorthpoleoftheloopelectromagnetandattractthesouthpole.Butoncethesouthpoleoftheloopelectromagnetwasnexttothenorthpoleofthepermanentmagnet,itwouldstaythere.Anypushontheloopwouldmerelysetitrockingaboutthisequilibriumposition.Bysandinghalfofoneendofthewire,youpreventcurrentfromflowingforhalfofeachspin.Themagneticfieldoftheloopelectromagnetisturnedoffforthathalf-spin.Asthesouthpoleoftheloopelectromagnetcomesclosesttothepermanentmagnet,theun-sandedwireturnsofftheelectriccurrent.Theinertiaoftherotatingcoilcarriesitthroughhalfofaturn,pasttheinsulatingpaint.Whentheelectriccurrentstartstoflowagain,thetwistingforceisinthesamedirectionasitwasbefore.Thecoilcontinuestorotateinthesamedirection.Extrainterestingtopicforth22ChargemovinginamagneticfieldobeystheRightHandRuleTherearetwotypesofRHRRightHandRule#1RightHandRule#2Chargemovinginamagneticfi23RightHandRule1ThethumbrepresentsthevelocityofwhichthechargeisgoingTheremainingfingerstellyouthedirectionofthemagneticfieldexample:RightHandRule1Thethumbrep24RightHandRule2I=directionofthechargeB=directionoftheMagneticFieldF=ForceactonthechargePalmPushPositive(*Remember!!)RightHandRule2I=direction25WhatisaFieldUBCPhysicsamp;AstronomyOutreachHome大學(xué)物理和天文學(xué)是一場宣傳家;課件26Slide22

ThetwodiagramsshowthepathofamovingelectroninamagneticfieldUseRHR#2toverifythepathoftheelectronsinthediagramsarecorrectSlide22Thetwodiagramsshow27RightHandRuleQuestion

PutaFerromagnet(NorS)closetheturnedonCRTfromtheside.Notethattheelectronbeamwilleithergoupwardordownward Q:Whatisthemagneticfield(NorS)onthesidefacingtheCRT? A:ItdependsonwhichsideIputmymagnetclosetotheCRT,butIjustusedRHR#2to identifiedtheNorSfieldontheFerromagnetRightHandRuleQuestionPuta28Magnetismexampleofpairandunpaired: Nisunpaired, Oispaired(oneofthem)Whatismagnetism? Magnetismisoneofthephenomenabywhichmaterialsexertanattractiveorrepulsiveforceonothermaterials.Whatcausesmagnetisminmaterial? Itistheunpairedelectronsintheelectronorbitcausemagnetism

Magnetismexampleofpairandu29RememberSPDF??(Chem11)ElectronsfallintoelectronshellaccordingtoHund’srule.ExamplesRememberSPDF??(Chem11)Elect30ExplanationofMagnetism

(forslide29and30)#1Explainwhatarepairedandunpairedelectrons#2RecalltheirChemistry11,SPDF,electronorbital

-UsingHund’srulesandPauliExclusionPrincipletoplaceelectronsintoelectronorbital -Practiceplacingelectronsintotheirorbitalusingthediagramonslide30ExplanationofMagnetism

(for31Nitrogen-Electrons-ProtonsandNeutrons1s22p3ElectronConfigurationofNitrogenWrongWrong2s2RightNitrogen-Electrons-Protonsand32ExplanationofMagnetism

(forslide32)ExerciseusingHund’srule -useNitrogenasanexample:thefirstelectronconfigurationisrightandthesecondand thirdexamplesoftheelectronconfigurationiswrongExplanationofMagnetism

(for33Therearefourtypesofmagnetism

1.Ferromagnetic2.Paramagnetic3.Diamagnetic4.Ferrimagnetic (Notgoingtocover)Therearefourtypesofmagnet34(forslide34)

TellstudentsthatFerrimagnetismistoohardtounderstand.TheyneedsomeuniversitylevelofPhysicsinordertounderstandit(forslide34)Tellstudentst35MaterialSusceptibilityχmVacuum0Water-1.2*10-5

Bi-16.6*10-5C-2.1*10-5O20.19*10-5Al2.2*10-5Fe200Co70Ni110MagnetismisMeasureinMagneticSusceptibility(χm)

Themoresusceptibilityofamaterialhas,themoremagneticpropertyitprocessesMaterialSusceptibilityχmVacuu36ExplanationofMagneticSusceptibility(forslide36)MagneticSusceptibilityistomeasurethemagneticpropertyofamaterial Q:Whatisthedifferencesbetweensomeofthematerialsinthechartinslide36? A:Theysplitoffintothreegroups: #1negativevaluewithsmallMagneticSusceptibility #2positivevaluewithsmallMagneticSusceptibility #3positivevaluewithrelativelybigMagneticSusceptibilitycomparetoabove #1and#2 #40MagneticSusceptibilityforVacuumbecausevacuumdoesnotcontain anymaterialExplanationofMagneticSuscep37FerromagneticAnymaterialthatpossessmagnetizationWITHOUTanexternalmagneticfieldisferromagneticlargeandpositivesusceptibilityExamplesofferromagneticmaterialsCobalt(Co)Susceptibility=70Iron(Fe)Susceptibility=200FerromagneticAnymaterialthat38ExplanationofFerromagnetic

(forslide38)Explainwhatisanexternalfield -example:currentrunningthroughasolenoidTheydonotneedanexternalfieldbecausethesematerialproducetheirownmagneticfield.Someferromagneticmaterialdoesnotproducetheirownmagneticfieldbecausethedomaininsideofthematerialdonotalign,whichIwillexplaininslide42.

ExplanationofFerromagnetic

(39IronelectronconfigurationFe:1s2,2s2,2p6,3s2,3p6,4s2,3d6

Fe:[Ar],4s2,3d6

Ar:1s2,2s2,2p6,3s2,3p6=[Ar]“Core”[Ar]-Theelectronsseemstoalignspontaneously-Purequantummechanicseffect

IronelectronconfigurationFe:40ExplanationofIron

(forslide40)AnotherexercisetofillintheelectronsintheelectronorbitalofIron.Discussthattherearefourunpairedelectronsinthe3dorbital #1ThisisoneofthereasonswhyIroncanproduceitsmagneticfield #2TheelectronsseemstoalignspontaneouslyduetoQuantumMechanicseffectsExplanationofIron

(forslid41WhyaresomeFerromagneticdoesn’tattractoneanother?HastodowiththemagneticdomainofthematerialWhyaresomeFerromagneticdoe42Explanationofdomainsofmaterial

(forslide42)Diagramontheleftshowsthedomainsofthematerialdonotalign.Thiscausesthemagneticfieldofthematerialcanceleachother,thereforeitcannotproduceitsownmagneticfieldDiagramontherightshowsthedomainsofthematerialdoalign.Therefore,itcanproduceamagneticfieldonitsown

Explanationofdomainsofmate43Ferromagneticmaterialdemo

Materialneeded -neodymiummagnet -coupleofpaperclipsInstructions #1Showthemthepaperclipsdonotattracttoanymaterialeventhoughtheyare ferromagnetic(domainsarenotalign). #2Attractoneofthepapercliptotheneodymiummagnet #3usethepaperclipthatisontheneodymiummagnettoattractanotherpaperclip Q:Howcomeitattractsnow? A:Theneodymiummagnethelpalignthedomaininthepaperclip #4Gentlyremovetheneodymiummagnetandshowthatthepaperclipcanstillattractto eachother Q:Why? A:ItstaysalignuntilyoupullthemawayFerromagneticmaterialdemoMa44ParamagneticAnymaterialthatpossessmagnetization(i.e.attractionwithothermagnetizedmaterial)WITHanexternalmagneticfieldisparamagneticsmallandpositivesusceptibilityExamplesofparamagneticmaterialsAluminumAlSusceptibility=2.2*10-5

PlatinumPtParamagneticAnymaterialthat45Paramagneticmaterialdemo

(forslide45)Trytoattractanaluminumcanwithaneodymiummagnet.Itcannot Q:Why? A:ItisbecauseoftheMagneticSusceptibilityofparamagneticmaterialsaretooweak comparedtoFerromagneticParamagneticmaterialdemo

(fo46Aluminumelectronconfiguration[Ne].3s2.3p1ComparetoIron(Fe)[Ar]Fe:[Ar],4s2,3d6thedipolesdonotinteractwithoneanotherandarerandomlyorientedintheabsenceofanexternalfieldduetothermalagitation,resultinginzeronetmagneticmoment

Whatisthedifferencesbetweenthetwo?!Aluminumelectronconfiguratio47ParamagneticandFerromagneticDemo(magnetsandlevitation)Instructionsofhowtousethelevitationdevice

#1Setupthedevice #2Placeorangestudwiththemagnetsidefacingawayfromthesolenoid #3Placethestudsoyoucanfeelthesolenoidisattractingthestud #4GentlyremoveyourhandsothedeviceanddoitsworkExplanationofhowitworks -solenoidprovidethemagneticfield,sothemagnetwillattractupward (paraandferromagneticproperty). -detectorinthebottomistosenseifthestudismovingupordown.Ifitmoves toohigh,thedetectorwillcutthecurrentsothestudwillcomebackdownby gravity.Ifitmovestoolow,thedetectorwillsendcurrentinthesolenoidto generateamagneticfield,sothestudwillgoupagainbytheattractionbetweenthemagnet andmagneticfieldParamagneticandFerromagnetic48VideoofferromagneticlevitationShowFerromagneticlevitationvideounder“Videos”Videoofferromagneticlevitat49Diamagneticveryweakandnegativesusceptibilitytomagneticfields.Negativesusceptibility=repelagainstmagneticfields(diamagnetism)Positivesusceptibility=attracttomagneticfields(para+ferromagnetism)Diamagneticveryweakandnegat50DiamagnetismExamplesofdiamagneticmaterialsGoldCopperHuman(mostly)DiamagnetismExamplesofdiamag51DiamagneticLevitationDemoInstructionsofhowtousethemagnets #1Setupthemagnets #2GentlyplacethepyrolyticcarboninthemiddleofthefourmagnetsDiamagneticLevitationDemoIns52ApplicationsofMagnetismMRI(magneticresonanceimages)SuperconductorsApplicationsofMagnetismMRI(53ApplicationofMagnetism

(forslide53)?MagneticResonanceImages(MRI)

-Thesemachinescanproducedupto7Teslatomakeverygoodimagesofthebody

Q: Howtoproduceastrongmagneticfield? A: Buildagiantsolenoid Q: Whatistheproblemwithproducingastrongmagneticfield A: #1Materialcannotstandthemagneticforcewiththemagneticfield;resultingin collapsingthematerial #2Highvelocityofcurrentrunningthroughthesolenoidproducealotofheat. Thiscanresultinmeltingthesolenoidifthemagneticfieldistoostrong?Superconductors -superconductorsareveryusefulbecauseitdoesnothaveanyresistantwithother material -allsuperconductorsarediamagnetic?Animals -AnimalssuchassharksandturtlesusetheEarthmagneticfieldtodetecttheirposition anddirection(Researchhasnotbeenfinished,afewpublishedpapersupportthistheory)ApplicationofMagnetism

(for54ApplicationsofMagnetismMaglevTrainsApplicationsofMagnetismMagle55Maglevtraindemo

InstructionofhowtousetheMaglevtrain #1Setupthetraintrack #2Placethetrainontothetrack #3PushthetrainDiscusstheproblemsthatthedemohad -toomuchfrictionfromthesideofthetrainbecausethisisaferromagneticlevitatedtrain(solutionisdiscussedinthenextslide).Therefore,thetrainwillmovesidetosidecausingfrictionwiththetrack -humangeneratedpower

MaglevtraindemoInstruction56ApplicationofMagnetismcon’t

(forslide55)WHY?

Q:whydopeopleinventMaglevtrains?

A:LessfrictionthantrainswithwheelsbecauseitdoesnotneedwheelstorunHOW? -firstitlevitatesusingsuperconductors

Q:Whydoweneedsuperconductorstolevitate,whycan’tweuseferromagneticmaterial likethetraininthedemo?

A:Theproblemwithusingferromagneticmaterialtolevitatethetrainisbecause ferromagneticmaterialwilltendtowanttoalignitselfwiththeopposingfield.Therefore, thetrainwillbeunstablemovingrightandleft(i.e.likethetraininthedemo).Thegood thingaboutsuperconductorsisbecausetheyarediamagnetic.Theywillalwaysopposea magneticfield,sotheywillnotmoveoutofthetracktryingtoalignwiththe

fieldlike ferromagneticmaterialsApplicationofMagnetismcon’t57ApplicationofMagnetismcon’t

(forslide55)Afterthetrainislevitated,thetraincanmoveforwardbythemagneticcoilfromtheside.ThesecoilcanflipfromNtoSandviceversatoattractandrepelagainstthemagnetsonthetrain(themagnetsonthetrainisfixedandcannotbeflipped.ApplicationofMagnetismcon’t58謝謝！供婁浪頹藍(lán)辣襖駒靴鋸瀾互慌仲寫繹衰斡染圾明將呆則孰盆瘸砒腥悉漠塹脊髓灰質(zhì)炎(講課2019)脊髓灰質(zhì)炎(講課2019)謝謝！供婁浪頹藍(lán)辣襖駒靴鋸瀾互慌仲寫繹衰斡染圾明將呆則孰盆瘸59Legend-WhitebackgroundisforTeachertoseeasinstructions.-BluebackgroundisfortheStudenttosee

Legend-Whitebackgroundisfor60Mypresentationismoregeartowardupperlevelhighschoolphysicsstudent(i.e.Physics11,Physics12andPhysics12AP).Mypresentationismoregeart61MaterialsneededforthedemonstrationsMaterialsneededfortheconstructionofthedemosPliersSandpaperGluegun#1CathoderaytubedemoCathoderaytubeset#2Batterydemo9Vbatterythincopperwiresrubberbandaneodymiummagnet(orderonlinegrand-illusions/toyshoporebay)#3Ferromagneticlevitationborrowalevitationdevicefromayear2

MechanicalEngineering2019friend#4Diamagneticlevitation4neodymiummagnetsapieceofpyrolyticcarbon

Materialsneededforthedemos.Instructionswillbegiveninlaterslides#5MaglevtrainStrongmagneticstripsthinplexiglassthesupporttrackMaterialsneededforthedemon62ElectromagnetismUniversityofBritishColumbiaPhysics420By:JasonCheungElectromagnetismUniversityof63WhatisaField?AregionofspacecharacterizedbyaphysicalpropertyhavingadeterminablevalueateverypointintheregionExamples:gravitationalfield,Electricfield,andmagneticfieldWhatisaField?Aregionofsp64ExplanationofField(#1)

(forslide5)Thismeansifweputanythingappropriateinafield,wecanthencalculate“something”outofthatfieldBeforegoingfurtherwithElectricfieldandMagneticfield,mentiontherearesomethingcalledtheElectricandMagneticfield.Usegravitationalfieldasastart,becauseG-fieldthemosteasytounderstandLinkElectricfieldandMagneticfieldafterexplainingtheGravitationalfieldExplanationofField(#1)

(fo65GravitationalFieldDefinedasA=accelerationG=gravitationalconstantm=massofbigobjectr=distancetothecenterofthebigobjectGravitationalFieldDefinedas66WhatisaFieldUBCPhysicsamp;AstronomyOutreachHome大學(xué)物理和天文學(xué)是一場宣傳家;課件67ExplanationofField(#2)

(forslide8)IfweputBobinthegravitationalfield,wecancalculatetheForceactingonhimbytheEarth.HewillfollowthegravitationalfieldlinesandfalltothesurfaceoftheEarth.Essentially,ifweputanythingthathasamassintheGravitationalfield,wecancalculatethat“something”Imentionedbefore.That“something”isthe“gravitationalforce”inthiscase.Emphasizethatwedeterminedifferentkindsofforcewithdifferentkindsoffield.ThiscanbridgetoElectricandMagneticFieldonfollowingslides.ExplanationofField(#2)

(for68ElectricFieldElectricfieldisdefinedastheelectricforceperunitChargeItisthesurroundingchargesthatcreateanelectricfieldE=ElectricFieldF=ElectricForceq=ChargeEismeasureinForce/CoulombElectricFieldElectricfieldi69ExplanationofElectricField(E-field)(forslide10)#0 Explainwhatisacharge,q -TheyshouldhaveenoughPhysicstoknowwhatisa+/-chargeis -OppositechargesattracteachotherandLikechargesrepeleachother#1 ExplainEisdefinedasF/q -Ifweputa+/-(positiveornegative)chargeinaelectricfield,the+/-chargewill experienceaforce.Thisforceiscalled“ElectricForce” -(IMPORTANT!!)RecallfromG-field.G-fieldrequiresanobjectwithaMASStohavea force.E-fieldrequiresa+/-chargetohaveaforce#2 HowdoyoudrawtheE-fieldlineswithdifferentcharges? -Electricfieldlinesalwayscomesoutofthepositivechargeintothenegative charge -NegativechargealwaysabsorbtheE-fieldlines

ExplanationofElectricField70ExplanationofElectricField(E-field)(forslide10)#3 Whatdirectionistheelectricforce? -ThedirectionoftheElectricforceisparalleltotheelectricfield. -LookatthePOINTPonthediagramonslide10.Thearrowinthediagramrepresents thedirectionoftheelectricforce Q: Whatisthecharge,positiveornegative,ifthedirectionofthe forceispointingoutwardlikeinthediagramonslide10 A: Positivebecauseitispointawayfromthestationarypositive charge Q: Whatisthecharge,ifthedirectionoftheforceonthediagram switched?? A: NegativechargeExplanationofElectricField71WhatisaFieldUBCPhysicsamp;AstronomyOutreachHome大學(xué)物理和天文學(xué)是一場宣傳家;課件72CathodeRayTubeDemo(CRT)InstructionandexplanationfortheCRTDemo#1 TurnonthePowersupplyandElectricplatecontroller,andwaitandcalibratetheelectronstothe centerofthescreen#2 AdjusttheelectricplatebyturningtheXknobortheYknob.Thisistodemonstratethatthe electricplatecancontrolwheretheelectronwillhitonthescreen.QuestionsandFunfactsQ: WhatdoyouthinkistheapplicationofaCRTandwhatdotheelectricplatesdointheCRT?A: Our“OLD”TV(beforeLCDandPlasma)usethistechniquetoviewimagesonourTV!CathodeRayTubeDemo(CRT)Ins73MagneticFieldMagneticfieldisafieldthatexertsaforceonamovingchargeAmagneticfieldcanbecausedeitherbyanothermovingchargeorbyachangingofelectricfieldormagneticdipolesofmaterialsMagneticFieldMagneticfieldi74ExplanationofMagneticfield

(forslide15)Inordertohaveamagneticforce,weneedamoving+/-charge.MagneticfieldlinescomeoutofNandgointoS(seediagramonslide15)Emphasizethe3componentstoproduceamagneticfield #1Moving+/-charge #2ChangingofE-field #3Dipoleofmaterial(seediagramtoexplain)

ExplanationofMagneticfield

75MagneticFieldismeasureinTeslaAsimpleformulatocalculateMagneticFieldB= magneticfieldF= MagneticForceQ= chargeV= velocityofthemovingchargeMagneticFieldismeasureinT76ExplanationofMagneticfieldcon’t

(forslide15)TheunitofTeslaisaverySMALLunit -Earthmagneticfieldhasaround10^(-5)Tesla -AverygoodFerromagnethasaround0.5to1TeslaItisveryhardtomakematerialthathasaverystrongmagneticfield,andIwillexplainitinmoredetaillaterSinceIamdoingaqualitativestudyonmagnetism,Ijustgavethemoneofthemostbasicequationformagneticforce -EmphasizeontheCROSSPRODUCT,itisnottreatedasatimesoperator.Velocityofa +/-chargeneedstobe90degreetothemagneticfieldinordertohaveamagneticforceExplanationofMagneticfield77Co