GCE A Level Physics 1976-2003 Topic 14 interferenc

Interferencersol'the,clcngthlo(part)ScreenFig.IrcpreserrtsaYouns'sslitsarrangelrent,inwhichr;isthewidthol'theprirnaryslitS,bitsdistnncefrolrthesccondaryslitsS,Sr,/tlreseparationol'tlrcsccondaryslitsandArtheseparationofthebrightbarrdsonthescreen.Il')istlrewavelengthofthemonochromaticlightused,thentheseparationArisN77/Il/9;J89/I/10InaYoung'sdoubleslitexperiment,asrnalldetecrorrrcasrrrcsanintensityofillurninationofIunitsatthecentreol'thcl'ringepattcrn.ll'oneofthetwo(identical)slitsisnowcovcled,themeasLrredintensityrvillbeAztRrcI_-Dl-El-^l224N77/tr/16Anirrtelf'erenceexperilnentissetupusingtwoidentical,coherentsourcesofIcmwaves,Fig.2shows,toscale,thepositionsofthesourcesP1andP2andoffiveobservationstations,AtoE.Whichstationwillbeatapositioncorrespondingtothcsecondol'f'-axisrnaximum?(Usearulerorapieceofgraphpaperasascalefbrrneasuringdistances.)axtsP'2''l)'EJ18/rUt6Whichonco1'thcl'ollolviltgstatelnentstnu.stbetlueirbouttworvave-trainsol'rnonochrotlaticlightarrivingatapointonascreeni1'tliewave-trainsarecoherent?A'fheyareinphase.BTheyhaveaconstantphasedit't'erence.C'l'lrcyhavebothtravelledpathsol'eclualIengtlr.DTheyhaveapproxirnatelyequalarnplitudes.ETheyinterf'ereconstructively,N78/llllIIntlrcYoung'sslitsarrangementshown,aJratternofequally-spacccl,parallelfiingesappearsonascreenplacedatS.WhichqLlantity,ifincreased,worrlclcausetheseparationtheli'ingestoincreasc?J77lltllz;J95lIl12WirvegeneratorsS1andS,generatewaveso1'equalwavelcngtlr,AtapointP,S,byitselfproclucesanoscillationo1'arnplitude2n,anrl52producesanoscillationol'arnplitudea,ilndthereisaphasedifl'erenceofnbetweenthcoscillations.WlrichgraphbcstrepresentstheresultoscillationatPwherrbotligeneratorsaleswitchedon?ABdisplacementdisplacementdisplacementdisplacemsnt14Interl'ercrrce(Superposition)'A'PhysicsTopicalPaPerl-ir'ocohcrcr)tnronochrolnlitic\\'ilvcsol'crlLlltlltntpiitttcleitreltrrtrglrttoqcthcrtolirrtttattitttcrl'crcnccpltttcfll()llirrjcfccn.Wlric:horrcol'thr:lirlltirvinggntphscottlcll.rrl)f.:scntlhcvlrriationolirttcrrsitYu'itlr1'rositirrrr.\'ll(;l'os.stlrc:plitcrrroll'rirrgcs/0t'rttt1c!()t'CItltc-fr,vowavegeneratorsS'wavclengtlr2rn.TheyarcrurrcladctcctorPi.splaccclassl-rowninthediagrarn.loucispeakersWherrastuclcntlnovesli'omXtoY,tlreintensityol'thenotehclrcarsisaltcrnutclylourliurdsol't.'fhcdistanccbetwecrracl.jlccrttloudarrclsol'trcgionstnaylrcrecluccclbydecreasirrgdistance11.incrcrtsingclisllncc/,.incr-cu:;iugthcanrltlituclc.dccrcasirrgthcanrplitude.tusingahiglierli'cclucncy.displacII.-lIlt,,III-rulIItCoherentIightisinciclentontwol'ineparallelslits,S1and52,Asshou,ninthcdia-urambclow(Fig.5)Aclarkl'r'ingeor:cursatcli1'{'crcncchetwccnthePr,vlrcn,nbcingnninteger,thepltasewovetrainsft'onrSraudSrisirTrrad(rr+r/r)rururl2lnnrdintensityTwoiclentic:alrrarr')',vslitsS,anclS,arcillurrinltctlbylighto{'rvavelcugthIfrotnliltointsourccI).Il',asslrorvnirrthcdiugr.amabove(Fig.3),thelightisthenallowedtol'allonascrecu,anclil'rliszlpositivcinteger,theconditionlitrdc.structivcinterl'crcnoeatQi.sthatt0ftrccliagmnr(frig.a)sliowstwosinrilarlouclspeakcrsdriveninpltaseI'r'omacolnmonaudio-l'reclrrcncysource.14Intellcrcrrcc(Superposition)12Sorrndll'omasrtlillloLrclspcltkcrl-rcirchcsaltointPbytrvoprthsu,liichclil'l'crinlcng{.hby1.2rn.Wltcnthcl'r'eclueitc:ycrl'thesourrrJisgraclulllyincrciisctl,tltcresultnrrtintcnsityatPgoesthrouglta.scric.so1'ntaxirnaantlniinirtrl.ArnaxinrrrnroccLlrsu,hcnthcl'recluencyis1000I-lzandthenertn.l'rximunroccr.trsat1200Ilz.Whatisthespeedol'sounclinthernccliumbetweenLandP?Whirtlrr'csuitlbler.rliresl'orr/anclLifinterl'cr-et)ccrll'irr,gcsr.rr.cIobclorrrrcilalongYY/ghtisthennleger,fhetherrotesrnayheTltediagrarnbclow(Fig.rn'angentcrrtthltprocluccsslit.L3Watcr-tt,avcgenct'ittorsS,anclS,gcnclitfcwavcsof'cclrrall'r'cc1Lrcnc1,.TIrelci.snophascclif'fcrcrrccLretwccrrthctlvogcr.lcl'iltol's.AtupointPsucltthat(SrP*S2P)isccpaltohall'Irvavclcngth,S,byit.sell'llroducesanoscillationoianrplitucle2at:rrdS:byitsell'producesanoscillationol'amplitudcrr.Whcnbothgencrittorsarcsrvitchedon,whiclroncol'thcgraplt.sbelowcorrcctlydescriLrcsthercsultantoscillatiorratP?displacementdisplacementdisplacemenldisplacernenldisplacenreni14CoherentlnicrowavesourccsSandS',placccladistirnccr/apartirsshownbelow(Fig.6),cnritwavcsol'rvavelength30rnrn.I4Irrtcrl'crcncc(Supcrposition)WlrenslitS,wascoveredwithshcrrvr.r,thcsepanrtioriofthelr-ingesincrczrsccl,thescparationo1'tlrefiingesdecreased.thefringepatternmovedtowardsX.thel'r'ingepatternmovedtowardsY.thescparationofthellingcsdecrczrsedintheregionOYbutwasunchangedintheregionOX.J84lIl/1316Whenrtwo-slitarrangernentwasseruproprocluceirtterfcrenccl'r'ingcsonilscfeenusingarnonochrorlriticsourccofgreenlight,thefr-ingeswereloundtobetooclosetogcthell'orci'lnvcnientobservatior-r.Inwhichofthefollorvingwayswoulditbcpossiblctoincreasethescparationol'tlreIringe.s'/ADccrensethedistancebetrveentlrescrccrrandthcslits.llIttclcasethcdistzurcebctrveenthesourccandthcslits.Cllavcalargcrdistancebetweenthetwoslits.DIncrcuscthcr,vidthol'eachslit.llReplacetheliglrtsolrrcelvithamonoc