speed of light questions - physical science 20...observation angle of incidence (i) angle of...
TRANSCRIPT
SpeedofLightQuestions
1. TheaveragedistancefromthesuntotheEarthis1.50×108km.Howlong(inminutes)doesittakeforsunlighttoreachtheEarth?
2. LightfromtheplanetUranustakes242min.toreachtheEarth.CalculatethedistancefromtheEarthtoUranus.
3. Incommunicatingwithanautomaticspacestation,radiosignalstravelingatthespeedoflightmusttraveladistanceof8.7×109meachway.Howlongdoesittakeforaradiosignaltotraveltothestationandback?
4. Alightyearisthedistancethatlighttravelsinoneyear.Howfar(inmeters)doeslighttravelin3.00years?
5. Onenanosecond(ns)is10-9s.Howfar,inmeters,doeslightactuallytravelin1.0ns?6. Thedistancetothemooncanbefoundwiththehelpofmirrorsleftonthemoonby
astronauts.ApulseoflightissenttothemoonandreturnstoEarthin2.562s.Usingthedefinedspeedoflight,calculatethedistancetothemoon.
7. Radiostationsareusuallyidentifiedbytheirfrequency.OneradiostationinthemiddleoftheFMbandhasafrequencyof99.0MHz.Whatisitswavelength?
8. Violetlighthasawavelengthof4.10x10-12m.Whatisthefrequency?9. Greenlighthasafrequencyof6.01x1014Hz.Whatisthewavelength?10. Whatisthewavelength(inmeters)ofaelectromagneticwavewithafrequencyof
640kHz?ANSWERS1. 8.33mins 2. 4.36x1012m 3. 58s4. 2.84x1016m 5. 0.30m 6. 3.84x108m7. 3.03m 8. 7.32x1019Hz 9. 4.99x10-7m10. 470m
RefractionandSnell’sLaw1. Lighttravelsthroughaliquidat2.50x108m/s.Findtheindexofrefractionofthat
liquid? 2. Whatisthespeedoflightinasubstancethathasanindexofrefractionof2.42?
Whatisthatsubstance? 3. Whatistheangleofrefractionwhenlightpassesfromairintodiamondatanangle
ofincidenceof60.0°?4. Lightpassesfromairintoanothersubstancethathasanindexof1.30.Iftheangleof
refractionis45.0°,thenwhatistheangleofincidence? 5. Amysteryobjectisinatankofwater.Alightbeaminthewaterstrikesthesurface
oftheobjectatanangleof42.2˚andrefractsintoitanangleof27.7˚.Findtheindexofthemysterysubstance.Whatmightthesubstancebe?
6. Whatisthespeedoflightinamediumiftheangleofincidenceinairis63ºandtheangleofrefractionis38º?
7. Atwhatangleofincidenceistherenorefraction? ANSWERS1. 1.20 2. 1.24x108m/s 3. 21.0˚4. 66.8˚ 5. 1.92 6. 2.07x108m/s7. 0˚
Refraction,TIRandCriticalAnglePractice
1. Medium1hasanindexofrefractionof1.20.Medium2hasanindexofrefractionof2.65.IfalightraypassesfromMedium2intoMedium1,willitberefractedtowardsorawayfromthenormal?
2. HowfarinkmwouldlighttravelinMedium1(fromquestion1)inthe2.0minutesthatittakesyoutocompletethisquestion?
3. Findthecriticalangleforadiamondinair.
4. Findthecriticalangleforadiamondinwater.
5. Alightrayinadiamondstrikethesurfaceatanangleof25˚.Findtheangleofrefractionifthediamondisinair.
6. Thecriticalangleforatypeofplasticis37.8˚.Findtheindexofrefractionofthatplasticandthespeedoflightintheplastic.
7. Thecriticalangleforafibreopticcableis24.624˚.Howlongwouldittakelighttotravelthrougha0.500kmlengthofthiscable?
8. Alightrayinwaterstrikesthesurfaceofcrownglassatanangleof79.4°tothenormal.Findtheangleofrefractioninsidetheglass?
9. Lighttravelinginflintglassstrikesaboundarywithanunknownsubstanceatanangleof65.2°.Thelightrefractstoanangleof71.6°intheunknownsubstance.Findtheindexandidentityoftheunknownsubstance.
10. Lighttravelinginethanolstrikesamysterysubstanceatanangleof78.0°tothenormal.Thelightisrefractedtoanangleof56.0°tothenormal.Whatisthespeedoflightinthemysterysubstance?
11. Lighttakes6.875x10-10stotravelthrougha12.5cmthickblockofplastic.Ifalightrayinairstrikestheblockatanangleofincidenceof32.5°,whatwouldtheangleofrefractionbeintheblock?
ANSWERS1. Away 2. 3.0x1010m 3. 24.4˚4. 33.3˚ 5. ??? 6. 1.63,1.84x108m/s7. 4.00x10–6s 8. 59.3° 9. 1.5410. 1.87x108m/s 11. 19.0°
Investigation:RefractionofLight–AirintoGlassProblem:Howislightrefractedwhenitpassesfromairintoanopticallydensermedium,likeglass?Materials:raybox(single-slit),semi-circularglassblock,polarco-ordinatepaperProcedure:
1. Placetheglassblockonthepolarco-ordinatepaperasshowninthepicture.Notethatthe0°lineactsasthenormalandshouldpassalongtheflatsurface.
2. Directasinglerayoflightattheflatsurfaceoftheglass,alongthenormal.Makeabsolutelysurethattheraypassesthroughthecenteroftheflatsurface.Measuretheangleofrefraction,andrecorditinthechartbelow.
3. Repeattheprocedureforanglesofincidenceof10°,20°,30°,40°,50°,and60°makingsuretorecordyourresultsinthechart.
4. Usingyourcalculator,determinethevaluesofthesinesofanglesofincidenceandrefraction.
5. Calculatetheratioofsini/sinRforeachpairofangles.Observation Angleof
Incidence(i)Angleof
Refraction(R)sini sinR sini/sinR
1 0° 2 10° 3 20° 4 30° 5 40° 6 50° 7 60°
Questions:
1. Whenlighttravelsfromairintoglasswithanangleofincidenceof0°,whathappenstoit?
2. Whenlighttravelsfromairintoglassatanangleofincidencegreaterthan0°,howisbentinrelationtothenormal?
3. Wherearetheincidentandrefractedrayslocatedinrelationtothenormal?
4. Howdoestheangleofrefractioncomparewiththeangleofincidenceineachcase?
5. Whatdoyounoteabouttheratioofsini/sinRforallcaseswheretheangleofincidenceis
>0°?
6. Iflighttravelsfromglassintoair,howdoyouthinkitwillbendinrelationtothenormal?
Investigation:RefractionofLight–GlassintoAirProblem:Howislightrefractedwhenitpassesfromglass(moredense)intoair(lessdense)?Materials:raybox(single-slit),semi-circularglassblock,polarco-ordinatepaperProcedure:
1. Placetheglassblockonthepolarco-ordinatepaperasshowninthepicture.Notethatthe0°lineactsasthenormalandshouldpassalongtheflatsurface.
2. Directasinglerayoflightatthecurvedsurfaceoftheglass,alongthenormal.Makeabsolutelysurethattheraypassesthroughthecenteroftheflatsurface.Measuretheangleofrefractionintheairandrecorditinthechartbelow.
3. Repeattheprocedureforanglesofincidenceof10°,20°,30°,40°,50°,and60°makingsuretorecordyourresultsinthechart.
4. Usingyourcalculator,determinethevaluesofthesinesofanglesofincidenceandrefraction.
5. Calculatetheratioofsini/sinRforeachpairofangles.6. Checktoseeatwhatangleofincidencetherefractedrayisat90°.
Observation Angleof
Incidence(i)Angleof
Refraction(R)sini sinR sini/sinR
1 0° 2 10° 3 20° 4 30° 5 40° 6 50° 7 60°
Questions:
1. Howwaslightrefractedwhentheangleofincidencewas0°?
2. Whenlighttravelsfromglassintoairatanangleofincidencegreaterthan0°,howisbentinrelationtothenormal?
3. Whichangleisalwaysgreater,theangleofincidenceortheangleofrefraction?
4. Wherearetheincidentandrefractedrayslocatedinrelationtothenormal?
5. Whatwastheaveragevalueofthesini/sinRrelationship?(ignorewhenθi=0°)
6. Whatistherelationshipbetweenthisvalueandthevaluefromstep5inthepreviouslab?
7. Whyistherenorefractionatthecurvedsurfaceinallcases?
8. Aboveapproximately45°,whathappenstoallthelight?
9. Atwhatangleofincidenceistheangleofrefraction90°?Determinethisvalue
mathematicallyaswellasexperimentally.
Investigation:ImagesFormedbyaConvergingLensProblems:1.Whatarethecharacteristicsandlocationsoftheimagesformedbyanobjectat
variouspositionsinfrontofaconverginglens? 2.Isthemirrorequationvalidforlenses?Materials:opticalbench,converginglens,lightsource,screenProcedure:1.Usethelenstofocusthelightfromadistantlightsourceontoascreen.Carefully
measurethefocallengthofthelensincentimeters.Turnthelensaroundandseeifitaffectsthefocallength.
2.Usingthevalueofthefocallengthinstepone,calculatethefollowingobjectdistances:2.5f,2.0f,1.5f,1.0f,and0.5f.Makeatablesimilartotheonebelowandrecordyourvalues.
3.Placethelensintheexactcenterofyouropticalbench. 4.Placethelightsourceat2.5f.Movethescreenuntilyoucaptureaclear,focused
imageonit.Recordtheimagedistanceandthecharacteristicsoftheimage. 5.Repeatstepfourfortheotherobjectdistances.Lookintothelensandviewthe
realimages.At0.5fyouwillnotbeabletoobtainanimageonthescreen.Lookintothelensforit.
ObjectDistance
ImageDistance
Characteristics 1𝑑𝑜
1𝑑𝑖
!!"+ !
!"
size attitude type2.5f= 2.0f= 1.5f= 1.0f= 0.5f= AnalysisQuestions1. Howdothefocallengthsforthetwosidesofthelenscompare?2. Astheobjectmovedfrom2.5ftowards1.0f,whathappenedtothe:
a. thesizeoftheimage?b. theimagedistance?c. theattitudeoftheimage?
3. Atwhatdistanceisitdifficulttoobtainaclearlyfocusedimage?4. Wherewouldyouplaceanobjectinrelationtothefocalpointtoobtain:
a. arealimage?b. avirtualimage?c. noimage
5. Determinethevalueof!!.Howdoesitcompareto !
!"+ !
!"forthefirstthreecases?
TheCowEyeDissectionLabWhatarethestructuresofthemammalianeyeandhowdotheyfunction?Themammalianeyeconsistsofmanyspecializedcellsandtissuesthatmakeupseveraldifferentstructures.Thestructureshavecertainfunctionsandtogether,theyformimagesthatareinterpretedbythebrain.Inthisinvestigation,youidentifythestructuresofacoweyeandlearntheirfunctions.ExternalfeaturesoftheeyeA.Locatethecornea,sclera,andopticnerve.
a. Thewhitepartoftheeye,thesclera,isatough,outercoveringoftheeyeball.Thescleragivestheeyeitsshapeandhelpstoprotectthedelicateinnerparts.
b. Thebluecoveringoverthefrontoftheeyeisthecornea.Whenthecowwasalive,thecorneawasclear.Togetherwiththelens,thecornearefractslightandhelpstheeyetofocus.Thecorneagivesalargercontributiontothetotalrefractionthanthelens.Thecurvatureofthecorneaisfixedwhilethatofthelensischangeable.Inyourcow’seye,thecorneamaybecloudy.
c. Youmaybeabletolookthroughthecorneaandseetheiris,thecoloredpartoftheeye,andthepupil,thedarkovalinthemiddleoftheiris.Atthebackoftheeyeistheopticnerve.Toseetheseparatefibersthatmakeuptheopticnerve,pinchthenervewithapairofscissorsoryourfingers.Ifyousqueezetheopticnerve,youmaygetsomewhitegoop.Thatismyelin,thefattylayerthatsurroundseachfiberofthenerve.Itisthenervethattransmitsvisualinformationfromtheeyetothebrain.
B.Examinethefatandmusclesurroundingtheeyeball.a. Withoutmovingyourhead,lookup.Lookdown.Lookallaround.Sixmusclesattachedtoyoureyeballmove
youreyesoyoucanlookindifferentdirections.Cowshaveonlyfourmusclesthatcontroltheireyes.Theycanlookup,down,left,andright,buttheycan’trolltheireyeslikeyoucan.Locatetheexternallyattachedmuscles.Thesemusclescontroleyemovementandhelpfocusimages.
b. Althoughthemusclesofeachindividualeyeworkasateam,theeyesthemselvesdonotfocusorworktogetheruntilmonthsafterbirth.However,oneeyeremainsdominant.Formacirclewithyourthumbandindexfinger.Holdthatpositionandplaceyourhandinfrontofyou.Withbotheyes,lookatsomethingthroughthecircle.Continuetoholdthatpositionandcloseoneeye;thenopenit.Closetheothereye.Theeyewhichisstillabletoviewtheobjectthroughthecircleisyourdominanteye.
c.Ifyoureachupandfeelaroundyoureye,you’llfeeltheboneofyourskull.There’syellowfatsurroundingyoureyeballtokeepitfrombumpingupagainsttheboneandgettingbruised.
C.Cutawaythefatandmuscle.D.Removethecornea–Usethephotosontheplacemattohelpyou.a. Useascalpeltomakeanincisioninthecornea.(Careful—don’tcut
yourself!)Cutuntiltheclearliquidunderthecorneaisreleased.Thatclearliquidistheaqueoushumor.It’smadeofmostlyofwaterandkeepstheshapeofthecornea.
b. Usethescalpeltomakeanincision(cut)throughthesclerainthemiddleof the
eye.
c. Useyourscissorstocutaroundthemiddleoftheeye,cuttingtheeyeinhalf.You’llendupwithtwohalves.Onthefronthalfwillbethecornea.Thecorneaismadeofprettytoughstuff—ithelpsprotectyoureye.Italsohelpsyouseebybendingthelightthatcomesintoyoureye.
d. Onceyouhaveremovedthecornea,placeitontheboard(orcuttingsurface)andcutitwithyourscalpelorrazor.Listen.Hearthecrunch?That’sthesoundofthescalpelcrunchingthroughlayersofcleartissue.Thecow’scorneahasmanylayerstomakeitthickandstrong.Whenthecowisgrazing,bladesofgrassmaypokethecow’seye—butthecorneaprotectstheinnereye.
E.Thenextstepistopullouttheiris.a. Theirisisbetweenthecorneaandthelens.Itmaybestucktothecorneaoritmayhavestayedwiththe
backoftheeye.Findtheirisandpullitout.Itshouldcomeoutinonepiece.b. Youcanseethatthere’saholeinthecenteroftheiris.That’sthepupil,theholethatletslightintotheeye.
Theiriscontractsorexpandstochangethesizeofthepupil.Indimlight,thepupilopenswidetoletlightin.Inbrightlight,thepupilshutsdowntoblocklightout.
c. Thebackoftheeyeisfilledwithaclearjelly.That’sthevitreoushumor,amixtureofproteinandwater.It’sclearsolightcanpassthroughit.Italsohelpstheeyeballmaintainitsshape.Thevitreoushumorisattachedtothelens.
F.Nowyouwanttoremovethelens.a. It’saclearlumpaboutthesizeandshapeofasquashedmarble. Thelensis
atransparentstructureintheeyethat,alongwiththecornea, helpstorefractandfocuslight.
b. Aringoftinyciliarymuscles,locatedalongtheinnersideofthe iris,connectsthelenstothemiddlelayeroftheeye.Ciliarymuscles contracttochangethecurvatureofthelens.
c. Thelensofthecow’seyefeelssoftontheoutsideandhardinthe middle.Holdthelensupandlookthroughit.Inalivingorganism,itiscompletelytransparent.(Youcowlensmaynotbetransparent.)Tofocusoncloserobjects,itgetsfattersoitcanrefractmorelight.
d. Putthelensdownonanewspaperandlookthroughitatthewordsonthepage.Ifyourlensistransparent,itshouldmagnify.
G.Nowit’stimetoexaminetheretina.a. Ifthevitreoushumorisstillintheeyeball,emptyitout.b. Ontheinsideofthebackhalfoftheeyeball,youcanseesome blood
vesselsthatarepartofathinfleshyfilm.Thatfilmistheretina. Beforeyoucuttheeyeopen,thevitreoushumorpushedagainsttheretinaso thatitlayflatonthebackoftheeye.Itmaybeallpushedtogetherinawad now.
c. Theretinaismadeofcellsthatcandetectlight.Theeye’slens usesthelightthatcomesintotheeyetomakeanimage,apicturemadeof light.Thatimagelandsontheretina.Thecellsoftheretinareacttothelightthatfallsonthemandsendmessagestothebrain.
d. Useyourfingertopushtheretinaaround.Theretinaisattachedto thebackoftheeyeatjustonespot.Canyoufindthatspot?That’stheplace wherenervesfromallthecellsintheretinacometogether.Allthesenervesgo outthebackoftheeye,formingtheopticnerve,thebundleofnervesthatcarries messagesfromtheeyetothebrain.Thebrainusesinformationfromthe retinatomakeamentalpictureoftheworld.
e. Thespotwheretheretinaisattachedtothebackoftheeyeiscalledtheblindspot.Becausetherearenolight-sensitivecells(photoreceptors)atthatspot,youcan’tseeanythingthatlandsinthatplaceontheretina.
H.Checkoutthetapetum.a.Undertheretina,thebackoftheeyeiscoveredwithshiny,blue-green stuff.Thisisthetapetum.Itreflectslightfromthebackoftheeye.Haveyoueverseen acat’seyesshiningintheheadlightsofacar?Cats,likecows,haveatapetum.Acat’s eyeseemstoglowbecausethecat’stapetumisreflectinglight.Ifyoushinealightata cowatnight,thecow’seyeswillshinewithablue-greenlightbecausethelight reflectsfromthetapetum.Humansdonothavethistapetum.I.Findyourblindspot.a.Tofindyourblindspot,usethetwodotsbelow.Holdonehandoveryourlefteyeandlookdirectlyattheleft-handdot.Atfirst,youcanseebothdotseventhoughyou'relookingdirectlyatonlyone.Asyouslowlymovethepageclosertoyoureyes,theright-handdotdisappears!Ifyoumoveyoureye,thedotwillreappear,butaslongasyoufocusonthefirstdot,thesecondwillbeinvisible.Moveevencloserandthemissingdotreappears.You’vefoundyourblindspot!
PW3Review
1.ThedistancefromSaskatoontoLucerne,Switzerlandis4575.2miles.Howlongwouldittakelighttotravelthere?2.UsainBoltranthe100mracein9.58seconds,fasterthananyotherhuman.Howfarwouldlighttravelinthattime?
3.Bluelighthasawavelengthof470nm.Whatisthefrequency?4.Yellowlighthasafrequencyof525THz.Whatisthewavelength?5.Lighttravelsthroughaliquidat2.81x108m/s.Findtheindexofrefractionofthatliquid?6.Whatisthespeedoflightinasubstancethathasanindexofrefractionof1.93?7.Whatistheangleofincidencewhenlightpassesfromairintodiamondwithanangleofrefractionof23.5°?8.Whatisthespeedoflightinamediumiftheangleofincidenceinairis24.0ºandtheangleofrefractionis19.8º?9.Findthecriticalangleforlighttravellingfromadiamondintowater.10.Thecriticalangleforanunknownsubstanceis42.3˚.Findtheindexofrefractionofthatsubstanceandthespeedoflightinthesubstance.
11.Thecriticalangleforanacrylicblockis41.3˚.Howlongwouldittakelighttotravelthrougha3.50cmblock?12.Lighttravels2.15x108m/sinanunknownsubstance.Ifalightrayinairstrikestheblockatanangleofincidenceof24.9°,whatwouldtheangleofrefractionbeintheblock?
13.Anobjectis3.0cmfromaconvexlensanditproducesavirtualimagethatis4.5cmfromthelens.Calculatethefocallength?
14.Themagnificationofaconverginglensis-0.45X.Ifanobjectis5.8cmtallandisplaced15.0cmfromthelens,calculatetheimageheightanddistance.
15.Ifanimageisproduced3.5cmfromadiverginglensthathasafocallengthof6.0cm,calculatetheobjectdistance.Iftheimageis0.75cmtall,whatistheobjectheightandmagnification?
16.Drawthefollowingtofindimagecharacteristicsinaconverginglens:a.f=4.0cmdo=7.5cmho=1.0cmb.f=3.5cmdo=7.0cmho=1.5cmc.f=6.5cmdo=3.0cmho=1.0cm17.Drawthefollowingtofindimagecharacteristicsinadiverginglens:a.f=4.0cmdo=7.5cmho=1.0cmb.f=7.0cmdo=7.0cmho=1.5cm18.Definethefollowingpartsoftheeye:
Ciliarymuscle Lens PupilSclera Opticnerve BlindspotVitreoushumour Aqueoushumour RetinaIris Cornea RodsCones
ANSWERSTONUMERICALQUESTIONS1.0.0244s 2.2.87x109m 3.6.4x1014Hz 4.5.71x10-7m5.1.07 6.1.55x108m/s 7.74.7° 8.2.50x108m/s9.33.3° 10.1.49;2.02x108m/s 11.1.77x10-10s12.17.6° 13.9.0cm 14.-2.6cm;6.8cm 15.8.4cm;1.8cm;0.42X16a.Real,inverted,larger b.Real,inverted,samesize c.Virtual,erect,larger17a.Virtual,erect,smaller b.???