IPhOexperimental competition.docx
- 文档编号:10260952
- 上传时间:2023-05-24
- 格式:DOCX
- 页数:12
- 大小:144.25KB
IPhOexperimental competition.docx
《IPhOexperimental competition.docx》由会员分享,可在线阅读,更多相关《IPhOexperimental competition.docx(12页珍藏版)》请在冰点文库上搜索。
IPhOexperimentalcompetition
ExperimentalCompetition
Saturday,June30th,2001
Pleasereadthisfirst:
1.Thetimeavailableis5hoursfortheexperimentalcompetition.
2.Useonlythepenprovided.
3.Useonlythefrontsideofthepaper.
4.Begineachpartoftheproblemonaseparatesheet.
5.Foreachquestion,inadditiontotheblanksheetswhereyoumaywrite,thereisananswerformwhereyoumustsummarizetheresultsyouhaveobtained.Numericalresultsshouldbewrittenwithasmanydigitsasareappropriatetothegivendata.
6.Writeontheblanksheetsofpapertheresultsofallyourmeasurementsandwhateverelseyouconsiderisrequiredforthesolutionofthequestion.Pleaseuseaslittletextaspossible;expressyourselfprimarilyinequations,numbers,figuresandplots.
7.FillintheboxesatthetopofeachsheetofpaperusedbywritingyourCountrynoandCountrycode,yourstudentnumber(StudentNo.),thenumberofthequestion(QuestionNo.),theprogressivenumberofeachsheet(PageNo.)andthetotalnumberofblanksheetsusedforeachquestion(TotalNo.ofpages).Writethequestionnumberandthesectionlabelofthepartyouareansweringatthebeginningofeachsheetofwritingpaper.Ifyouusesomeblanksheetsofpaperfornotesthatyoudonotwishtobemarked,putalargeXacrosstheentiresheetanddonotincludeitinyournumbering.
8.Attheendoftheexam,arrangeallsheetsinthefollowingorder;
∙answerform
∙usedsheetsinorder
∙thesheetsyoudonotwishtobemarked
∙unusedsheetsandtheprintedquestion
Placethepapersinsidetheenvelopeandleaveeverythingonyourdesk.Youarenotallowedtotakeanysheetsofpaperandanymaterialusedintheexperimentoutoftheroom.
ROTATINGLIQUID
Thisexperimentconsistsofthreebasicparts:
1.investigationoftheprofileoftherotatingliquid’ssurfaceandthedeterminationoftheaccelerationduetogravity,
2.investigationoftherotatingliquidasanopticalsystem,
3.determinationoftherefractiveindexoftheliquid.
Whenacylindricalcontainerfilledwithaliquidrotatesabouttheverticalaxispassingthroughitscenterwithauniformangularvelocity,theliquid’ssurfacebecomesparabolic(seeFigure1).Atequilibrium,thetangenttothesurfaceatthepointP(x,y)makesananglewiththehorizontalsuchthat
(1)
whereRistheradiusofthecontainerandgistheaccelerationduetogravity.
Itcanfurtherbeshownthatfor atx=x0= y(x0)=h0 (2) thatis;theheightoftherotatingliquidisthesameasifitwerenotrotating. Theprofileoftherotatingliquid’ssurfaceisaparaboladefinedbytheequation (3) wherethevertexisatV(0,y0)andthefocusisatF(0,y0+C).Whenopticalraysparalleltotheaxisofsymmetry(opticalaxis)reflectattheparabolicsurface,theyallfocusatthepointF(seeFig.1). Apparatus ∙Acylindricalrigidplasticcupcontainingliquidglycerin.Millimetricscalesareattachedtothebottomandthesidewallofthiscup. ∙Aturntabledrivenbyasmalldcelectricmotorpoweredbyavariablevoltagesupply,whichcontrolstheangularvelocity. ∙Atransparenthorizontalscreenonwhichyoucanputtransparentorsemi-transparentmillimetricscales.Thelocationofthescreencanbeadjustedalongtheverticalandhorizontaldirections. ∙Alaserpointermountedonastand.Thepositionofthepointercanbeadjusted.Theheadofthepointercanbechanged. ∙Additionalheadforthelaserpointer. ∙Aruler. ∙Ahighlighterpen. ∙Astopwatch.Pushtheleftbuttontoreset,themiddlebuttontoselectthemode,andtherightbuttontostartandstopthetiming. ∙Transmissiongratingswith500or1000lines/mm. ∙Bubblelevel. ∙Glasses. IMPORTANTNOTES ∙DONOTLOOKDIRECTLYINTOTHELASERBEAM.BEAWARETHATLASERLIGHTCANALSOBEDANGEROUSWHENREFLECTEDOFFAMIRROR-LIKESURFACE.FORYOUROWNSAFETYUSETHEGIVENGLASSES. ∙Throughoutthewholeexperimentcarefullyhandlethecupcontainingglycerin. ∙Theturntablehasalreadybeenpreviouslyadjustedtobehorizontal.Usebubblelevelonlyforhorizontalalignmentofthescreen. ∙Throughouttheentireexperimentyouwillobserveseveralspotsonthescreenproducedbythereflectedand/orrefractedbeamsatthevariousinterfacesbetweentheair,theliquid,thescreen,andthecup.Besuretomakeyourmeasurementsonthecorrectbeam. ∙Inrotatingtheliquidchangethespeedofrotationgraduallyandwaitforlongenoughtimesfortheliquidtocomeintoequilibriumbeforemakinganymeasurements. EXPERIMENT PART1: determinationofgUsingaRotatingLıquıd[7.5pts] ∙DeriveEquation1. ∙Measuretheheighth0oftheliquidinthecontainerandtheinnerdiameter2Rofthecontainer. ∙Insertthescreenbetweenthelightsourceandthecontainer.MeasurethedistanceHbetweenthescreenandtheturntable(seeFigure2). ∙Alignthelaserpointersuchthatthebeampointsverticallydownwardandhitsthesurfaceoftheliquidatadistancex0= fromthecenterofthecontainer. ∙Rotatetheturntableslowly.Besurethatthecenteroftherotatingliquidisnottouchingthebottomofthecontainer. ∙Itisknownthatatx0= theheightoftheliquidremainsthesameastheoriginalheighth0,regardlessoftheangularspeed.Usingthisfactandmeasurementsoftheangleofthesurfaceatx0forvariousvaluesof,performanexperimenttodeterminethegravitationalaccelerationg. ∙Preparetablesofmeasuredandcalculatedquantitiesforeach. ∙Producethenecessarygraphtocalculateg. ∙Calculatethevalueofgandtheexperimentalerrorinit ∙Copythevalues2R,x0,h0,Handtheexperimentalvalueofganditserrorontotheanswerform. PART2: OpticalSystem Inthispartoftheexperimenttherotatingliquidwillbetreatedasanimageformingopticalsystem.Sincethecurvatureofthesurfacevarieswiththeangularspeedofrotation,thefocaldistanceofthisopticalsystemdependson. 2a)Investigationofthefocaldistance[5.5pts] ∙Alignthelaserpointersuchthatthelaserbeamisdirectedverticallydownwardatthecenterofthecontainer.MarkthepointPwherethebeamstrikesthescreen.Thusthelinejoiningthispointtothecenterofthecupistheopticalaxisofthissystem(seeFigure2). ∙Sincethesurfaceoftheliquidbehaveslikeaparabolicmirror,anyincidentbeamparalleltotheopticalaxiswillpassthroughthefocalpointFontheopticalaxisafterreflection. ∙Adjustthespeedofrotationtolocatethefocalpointonthescreen.MeasuretheangularspeedofrotationandthedistanceHbetweenthescreenandtheturntable. ∙RepeattheabovestepsfordifferentHvalues. ∙Copythemeasuredvaluesof2Randh0andthevalueofateachHontotheanswerform. ∙Withthehelpofanappropriategraphofyourdata,findtherelationshipbetweenthefocallengthandtheangularspeed.Copyyourresultontotheanswerform. 2b)Analysisofthe“image”(whatyouseeonthescreen)[3.5pts] Inthispartoftheexperimentthepropertiesofthe“image”producedbythisopticalsystemwillbeanalyzed.Todoso,followthestepsgivenbelow. ∙Removetheheadofthelaserpointerbyturningitcounterclockwise. ∙Mountthenewhead(providedinanenvelope)byturningitclockwise.Nowyourlaserproducesawelldefinedshaperatherthananarrowbeam. ∙Adjustthepositionofthelaserpointersothatthebeamstrikesataboutthecenterofthecupalmostnormally. ∙Putasemitransparentsheetofpaperonthehorizontalscreen,whichisplacedclosetothecup,suchthatthelaserbeamdoesnotpassthroughthepaper,butthereflectedbeamdoes. ∙Observethesizeandtheorientationofthe“image”producedbythesourcebeamandthebeamreflectedfromtheliquidwhenitisnotrotating. ∙Starttheliquidrotating,andincreasethespeedofrotationgraduallyuptothemaximumattainablespeedwhilewatchingthescreen.Asincreasesyoumightobservedifferentfrequencyrangesoverwhichthepropertiesofthe“image”aredrasticallydifferent.Todescribetheseobservationscompletethetableontheanswerformbyaddingarowtothistableforeachsuchfrequencyrangeandfillitinbyusingtheappropriatenotationsexplainedonthatpage. PART3: RefractiveIndex[3.5pts] Inthispartoftheexperimenttherefractiveindexofthegivenliquidwillbedeterminedusingagrating.Whenmonochromaticlightofwavelengthisincidentnormallyonadiffractiongrating,themaximaofthediffractionpatternareobservedatanglesmgivenbytheequation (4) where,mistheorderofdiffractionanddisthedistancebetweentherulingsofthegrating.Inthispartoftheexperimentadiffractiongratingwillbeusedtodeterminethewavelengthofthelaserlightandtherefractiveindexoftheliquid(seeFigure3). ∙Usethegratingtodeterminethewavelengthofthelaserpointer.Copyyourresultontotheanswerform. ∙Immersethegratingperpendicularlyintotheliquidatthecenterofthecup. ∙Alignthelaserbeamsuchthatitenterstheliquidfromthesidewallofthecupandstrikesthegratingnormally. ∙Observethediffractionpatternproducedonthemillimetricscaleattachedtothecupontheoppositeside.Makeanynecessarydistancemeasurements. ∙Calculatetherefractiveindexnoftheliquidbyusingyourmeasurements.(Ignoretheeffectoftheplasticcuponthepathofthelight.) ∙Copytheresultofyourexperimentontotheanswerform. P(x,y) Figure1.DefinitionsofthebankangleatpointP(x,y),thevertexVandthefocusFforthep
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- IPhOexperimental competition