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TABLEOFCONTENTS

Introduction...............................................................................................................................................................................................................3

EducationalGoalsforLight1.............................................................................................................................................................................4

MasterMaterialsListforAllLabs.....................................................................................................................................................................5

LabSafety...................................................................................................................................................................................................................6

Lesson#1:RainbowShadows...........................................................................................................................................................................7

Lesson#2:Kaleidoscopes..................................................................................................................................................................................10

Lesson#3:LiquidPrism.....................................................................................................................................................................................13

Lesson#4:LunarPhases....................................................................................................................................................................................16

Lesson#5:SkyinaJar.........................................................................................................................................................................................20

Lesson#6:LightTricks.......................................................................................................................................................................................22

Lesson#7:BlackLightTreasureHunt.........................................................................................................................................................24

Lesson#8:Benham’sDisk.................................................................................................................................................................................28

Lesson#9:EyeBalloon.......................................................................................................................................................................................31

Lesson#10:DisappearingFrog.......................................................................................................................................................................34

Lesson#11:PinholeCamera............................................................................................................................................................................36

Lesson#12:Diffraction......................................................................................................................................................................................39

Lesson#13:SpeedofLight...............................................................................................................................................................................42

Lesson#14:MixingColors................................................................................................................................................................................45

Lesson#15:MixingColdLight.........................................................................................................................................................................47

Lesson#16:RefractiveIndex...........................................................................................................................................................................50

Lesson#17:FireandOptics.............................................................................................................................................................................53

Lesson#18:SimpleMicroscopes&Telescopes.......................................................................................................................................56

Light1Evaluation.................................................................................................................................................................................................59

Light1Quiz..............................................................................................................................................................................................................60

Light1LabPractical.............................................................................................................................................................................................62

AnswerstoExercisesandQuizzes.................................................................................................................................................................63

VocabularyfortheUnit.......................................................................................................................................................................................66

Introduction

Greetingsandwelcometothestudyoflight.Thisunitwascreatedbyamechanicalengineer,universityinstructor,airplanepilot,astronomer,robot‐builderandrealrocketscientist…me!IhavethehappyopportunitytoteachyoueverythingIknowaboutelectricityoverthenextsetoflessons.Ipromisetogiveyoumybeststuffsoyoucantakeitandrunwithit…orfly!

Togetthemostoutoftheselabs,therearereallyonlyacoupleofthingstokeepinmind.Sinceweareallheretohavefunandlearnsomethingnew,thisshouldn’tbetoohard.

Oneofthebestthingsyoucandoasthestudentistocultivateyourcuriosityaboutthings.Whydidthatmove?Howdidthatspin?What’sreallygoingonhere?

Thisunitonlightischockfullofdemonstrationsandexperimentsfortwobigreasons.First,they’refun.Butmoreimportantly,thereasonwedoexperimentsinscienceistohoneyourobservationalskills.ScienceexperimentsreallyspeakforthemselvesmuchbetterthanIcaneverputintowordsorshowyouonavideo.AndI’mgoingtohityouwithalotofthesesciencedemonstrationsandexperimentstohelpyoudevelopyourobservingtechniques.

Scientistsnotonlylearntoobservewhat’sgoingonintheexperiment,buttheyalsolearnhowtoobservewhattheirexperimentistellingthem,whichisfoundbylookingatyourdata.It’snotenoughtoinventsomenewkindofexperimentifyoudon’tknowhowitwillperformwhentheconditionschangeabit,likeonMars.We’regoingtolearnhowtopredictwhatwethinkwillhappen,designexperimentsthatwilltestthisidea,andlookovertheresultswegottofigureoutwheretogofromthere.Scienceisaprocess,it’sawayofthinking,andwe’regoingtogetplentyofpracticeatit.

Goodluckwiththisunitonthemagicoflight!

FortheParent/Teacher:EducationalGoalsforLight1

Scientistarestilltryingtomakeheadsortailsofthisthingcalledlight,andnearastheycantell,itsometimesinteractslikeaparticle(likeamarble)andothertimeslikeawave(likeontheocean),andyoureallycan’tseparatethetwobecausetheyactuallycomplementeachother.

Energycantakeoneoftwoforms:matterandlight(calledelectromagneticradiation).Lightisenergyintheformofeitheraparticleorawavethatcantravelthroughspaceandsomekindsofmatter,likeglass.We’regoingtoinvestigatethewildworldofthephotonthathasbaffledscientistsforoveracentury.Lowelectromagneticradiation(calledradiowaves)canhavewavelengthslongerthanafootballfield,whilehigh‐energygammarayscandestroylivingtissue.

Herearethescientificconcepts:

Lighthasasourceandtravelsinadirection. Sunlightcanbeblockedtocreateshadows. Lightisreflectedfrommirrorsandothersurfaces. Thecoloroflightstrikinganobjectaffectshowoureyesseeit. Weseeobjectswhenlighttravelingfromanobjectentersoureye. Lightcantravelthroughavacuum,likespace. Lightcanchangespeeds,butthemaximumspeedisthroughavacuum(186,000milespersecond). Thethreeprimarycolorsoflightarered,blue,andgreen.Redandgreenlightmixedtogethermakeyellow

light. Prismsun‐mixlightintoitscolorsorwavelengths. Lightchangesspeedswhenitpassesthroughadifferentmaterial. Lensesworktobendlightinacertaindirection,calledrefraction. Concavelensesworktomakeobjectssmallerandconvexlensesmakethemlarger.

Bytheendofthelabsinthisunit,studentswillbeableto:

Designandbuildasimplerefractortelescopeusinglenses. Knowhowtodemonstratehowcompoundmicroscopeswork. Understandhowtodeterminehowtomeasurethespeedoflight. Differentiateobservationfrominference(interpretation)andknowscientists’explanationscomepartly

fromwhattheyobserveandpartlyfromhowtheyinterprettheirobservations. Formulateandjustifypredictionsbasedoncause‐and‐effectrelationships. Conductmultipletrialstotestapredictionanddrawconclusionsabouttherelationshipsbetween

predictionsandresults. Constructandinterpretgraphsfrommeasurements.

Followasetofwritteninstructionsforascientificinvestigation.

MasterMaterialsListforAllLabs

Thisisabrieflistofthematerialsthatyouwillneedtodoalloftheactivities,experimentsandprojectsinthisunit.Thesetofmaterialslistedbelowisjustforonelabgroup.Ifyouhaveaclassof10labgroups,you’llneedtoget10setsofthematerialslistedbelow.Mostmaterialsarereusable.

12”fishingline 12”string 12”thread 12”yarn 8indexcards slicedcheese(individuallywrapped) babyoil ball biconvexplasticlens bookofmatches box calculator CDorDVD chocolatebar(extra‐largebarsworkbest) chocolatechips cleartape crayonsORmarkers darkeveninginsideyourhouse darkroom diffractiongrating disposablecups(6) dollarbill feather fingernailpolish(red,yellow,green,blue) fireextinguisher flashlight glassjar(2) gloves

gluestick goggles handheldmagnifyinglenses(2) indexcards laser(optional) meterstick(2) microwave(onlyoneforentireclass) milkorflour minimarshmallows nail paper paperplates paperclip pencil penny razororscissors red,green,andbluetrue‐colorlightsticks roundballoon,white,9inches rubbingalcohol scrappieceofcardboard strainer,suchasacoffeefilter tack tape tracingpaper UVblackfluorescentlight votivecandle water

LabSafetyGoggles:Theseshouldbewornwhenworkingwithchemicals,heat,fire,orprojectiles.Theseprotectyoureyesfromchemicalsplatter,explosions,andtinyfast‐movingobjectsaimedattheeyes.Ifyouwearglasses,youcanfindgogglesthatfitoverthem.Don’tsubstituteeyeglassesforgoggles,becauseofthelackofsideprotection.Eyeglassesdon’tprovidethisimportantsideeyeprotection.

CleanupMesses:Yourlabareashouldbeneat,organized,andspotlessbeforeyoustart,duringyourexperiment,andwhenyouleave.Scientistswastemoretimehuntingforlostpapers,piecesofanexperiment,andtryingtorepositionsensitiveequipment…allofwhichcouldhaveeasilybeenavoidedhadtheybeentaughtorganizationalskillsfromthestart.

DisposeofPoisons:Ifapoisonoussubstancewasused,created,orproducedduringyourexperiment,youmustfollowtheproperhandlingproceduresfordisposal.You’llfinddetailsforthisintheexperimentsasneeded.

SpecialNotesonBatteries:Donotusealkalinebatterieswithyourexperiments.Findthesuper‐cheapkindofbatteries(usuallylabeled“HeavyDuty”or“SuperHeavyDuty”)becausethesetypesofbatterieshaveacarbon‐zinccore,whichdoesnotcontaintheacidthatalkalinebatterieshave.Thismeanswhenyouwireupcircuitsincorrectly(whichyoushouldexpecttodobecauseyouarelearning),thecircuitswillnotoverheatorleak.Ifyouusealkalinebatteries(likeEnergizerandDuracell)andyourstudentsshortacircuit,theirwiresandcomponentswillgetsuper‐hotandleakacid,whichisverydangerous.

NoEatingorDrinkingintheLab:Allfoodsanddrinksarebannedfromyourclassroomduringscienceexperimentation.Whenyoueatordrink,youruntheveryrealriskofingestingpartofyourexperiment.Forelectricityandmagnetismlabs,alwayswashyourhandsafterthelabisovertorinseofftheleadfromtheelectricalcomponents.

NoHorsePlay:Whenyougoofaround,accidentshappen,whichmeanschemicalsspill,circuitsshort,andallkindsofhazardscanoccurthatyouweren’texpecting.Neverthrowanythingtoanotherpersonandbecarefulwhereyouputyourhands–itcouldbeinthemiddleofasensitiveexperiment,especiallywithmagnetismandelectricity.Youdon’twanttoruntheriskofgettingshockedorelectrifiedwhenit’snotpartofyourexperiment.

Fire:Ifyouthinkthere’safireintheroom(evenifyou’renotsure),letyourteacherknowrightaway.Iftheyarenotaround(theyalwaysshouldbe),smotherthefirewithafireblanketoruseafireextinguisherandsendsomeonetofindanadult.Stop,drop,androll!

Questions:Ifyou’renotsureaboutsomethingstopandask,nomatterwhatit’sabout.Ifyoudon’tknowhowtoproperlyhandleachemical,dopartofanexperiment,ask!Ifyou’renotcomfortabledoingpartoftheexperiment,thendon’tdoit.

Lesson#1:RainbowShadows

Overview:Imagineyou’reapainter.Whatthreecolorsdoyouneedtomakeupanycolorintheuniverse?(Youshouldbethinking:red,yellow,andblue…andyes,youarerightifyou’rethinkingthattherealprimarycolorsarecyan,magenta,andyellow,butsomefolksstillprefertothinkoftheprimarycolorsasred‐yellow‐blue…eitherway,it’sreallynotimportanttothisexperimentwhichprimarysetyouchoose.)

Here’satrickquestion–canyoumakethecolor“yellow”withonlyred,green,andblueasyourcolorpalette?Ifyou’reascientist,it’snotaproblem.Butifyou’reanartist,you’reintroublealready.Thekeyismixinglight,notpaint.

WhattoLearn:Thethreeprimarycolorsoflightarered,blue,andgreen.Redandgreenlightmixedtogethermakeyellowlight.Sunlightcanbeblockedtomakeshadows.

Materials

flashlights(3) fingernailpolish(red,green,andblue) cleartape(NOTtranslucent) awhitewall(oranotherlargewhitesurface)

Experiment

1. Makeyourroomasdarkaspossibleforthisexperimenttowork.2. Covereachflashlightlenscompletelywiththecleartape.Besuretogettheedgesandaroundtherim.3. Paintoneflashlight’stapelayerred,oneblue,andonegreen.Makesuretherearenounpaintedspots.4. Allowthenailpolishtodry.5. Turnoffallthelights.6. Shinetheflashlightstogetherontoawhitewall.Whatcoloristhewall?Recorditonyourchart7. Nowturnofftheredflashlight.Whatcolordoyouseenow?Recordyourobservation.8. Placeyourhand,apencil,oranotherobjectinfrontoftheflashlight.Waveitaroundabit.Whatcolor

shadowsdoyouseeonthewall?9. Experimentwiththedifferentcolorcombinationswhilefillingoutthechartwithyourobservations.

RainbowShadowsDataTable

Lens#1Color Lens#2Color ShadowColor

Reading

Theuniverseismadeofmatterandenergy.Matterisanythingthathasmass,andallordinarymatterexistsinfourstates,whichwecoverinourChemistryunit.Electromagneticradiation(EM)isenergyintheformofwavesorparticlesthatareemittedfromasourceandtravelthroughspaceandeventhroughcertainkindsofmatter.

Visiblelightisaformofenergythatwecanseewithoureyes,andtheorganelles(calledconesandrods)collectlightfromimagesthatweseeandtransmitthesetothebrain.Visiblelightmakesupatinypartoftheelectromagneticspectrum.Thisenergycanbemeasuredandspecifiedbyitsintensity(howbright),frequency(wavelength),polarization(thedirectionoftheelectricfield),andphase(timeshift).

Whitelightmakesupallthecolorsoftherainbow:red,orange,yellow,green,blue,andpurple.Prismscanun‐mixlightintotheindividualcolorsbybendingthelightbydifferentamounts.Thered,green,andbluearetheprimarycolorsoflightthatmixtogethertoformeveryothercolorwesee.

Whenlightstrikesasurface,itcantravelthroughthesurfacecompletely,partially,orbeentirelyreflectedback,dependingonthesurfaceitstrikes.Lightcanalsoenteramaterialandgetcompletelytrappedinsidebyinternalreflections.Insomecases,lightcanbeabsorbed,andwhenthishappens,theabsorbingmaterialcanheatup,changecolor,changestate,orre‐transmitthelightatacompletelydifferentwavelength.

Lightcanbefilteredanddissectedintoaspecialsignaturethatallowsscientiststoidentifythepatternsandbeabletotellwhichelementgeneratedthelightinthefirstplace.Thesepatterns,orlightsignatures,areusedextensivelybyastronomersandchemiststodeterminethepropertiesofthelightandthechemicalreactionsrequiredtogeneratethelight.

Mostlightisn’tdetectablebythehumaneye,whichmakesstudyinglightmorelikeinvestigatingacrimescene.You’llquicklybepuzzlingthepiecestogethertoexplainwhypencilsbreakinaglassofwater,howtofocuslightenergytofryeggs,andhowlensesbendlighttodistortandmagnifyimagesintelescopes.

Mixingthethreeprimarycolorsoflightgiveswhitelight.Ifyoutookthreelightbulbs(red,green,andblue)andshinedthemontheceiling,you’dseewhite.Andifyoucouldmagicallyun‐mixthewhitecolors,you’dgettherainbow(whichisexactlywhatprismsdo).

Ifyou’rethinkingyellowshouldbeaprimarycolor–itisaprimarycolor,butonlyintheartist’sworld.Yellowpaintisaprimarycolorforpainters,butyellowlightisactuallymadefromredandgreenlight.(Easywaytorememberthis:thinkofChristmascolors–redandgreenmergetomaketheyellowstarontopofthetree.)

Troubleshooting:Thisexperimenthasafewthingstobeawareof.Ifyou’renotgettingthecoloredshadows,checktobesurethattheflashlightisbrightenoughtoilluminateawallinthedark.Besuretoshutthedoors,shades,windows,anddrapes.Inthedark,whenyoushineyourredflashlightonthewall,thewallshouldglowred.Bewareofusingoff‐colornailpolish–makesureit’sreallyred,nothotpink.Alternately,youcouldusebrightly‐coloredcellophane.Ifyoustillneedhelpmakingthisexperimentwork,youcanvisityourlocalhardwarestoreandfindthreefloodlampholders(thecheapclamp‐styleonesmadefromaluminumworkwell–you’llneedthree)andscrewincolored“partylights”(makeonered,onegreen,andoneblue),whicharecoloredincandescentbulbs.Thesewillprovidealotmorelight!Youcanalsoaddafourthyellowlighttofurtherillustratehowyellowlightisn’taprimarycolor.Tryusingonlyred,yellow,andblue…you’llquicklyfindthatyoucan’tobtainallthecolorsasyoucouldwiththeoriginalred‐green‐bluelights.Exercises

1. Whatarethethreeprimarycolorsoflight?

2. Whatcolordoyougetwhenmixingtheprimarycolorsoflight?

3. Howdoyoumixtheprimarycolorsoflighttogetyellow?

4. Usecrayonsorcoloredpencilstodrawwhatyousawwhenallthreelightswereshiningonthewallandyouwavedyourhandinfrontofthelight.

Lesson#2:Kaleidoscopes Overview: Inthesimplestsense,akaleidoscopeisatubelinedwithmirrors.Whetheryouleavetheendopenortapeonabagofbeadsisuptoyou,butthemainideaistoprovideenoughofanopticalillusiontowowyourfriends.Kaleidoscopesareanexampleofusinglightreflectors,whichdon’tgiveoffanylight,butstillbouncelightbacktoyoureyes. Thefirstkaleidoscopeswereconstructedin1816byascientistwhilestudyingpolarization(you’lllearnmoreaboutpolarizationinafuturelesson).Kaleidoscopeswerequicklypickedupasanamusementgadgetbythepublicandhavestayedwithuseversince.Todayyouwillbemakingyourveryownkaleidoscope.

WhattoLearn:Kaleidoscopesareanexampleofusinglightreflectors,whichdon’tgiveoffanylight,butstillbouncelightbacktoyoureyes. Lightisreflectedfrommirrorsandothersurfaces.

Materials

MirrorKaleidoscope

4‐5mirrors,allthesamesize tape scissors

MylarKaleidoscope

Mylar indexcardorpieceofcardboard hotgluegun scissors

Experiment

MirrorKaleidoscope

1. Layoutastripoftape,stickysideup.2. Centeronemirroronthetapewithitsreflectivesidepointingup.3. Attachthesecondandthirdmirrorsclosetothefirstat90‐degreeangles.Onewillbeontheleft;theother

willbeontheright.4. Riptheexcesstapeoffofoneendandthencarefullytapetogetherthethreeidenticalmirrors,forminga

triangularshape.Makesurethatthereflectivesurfaceisontheinside.5. Tapealltheroughedgesverywellandpeekthroughtheopeningasyouwalkaround.6. Lookattheimagesthemirrorsmakeontheinsidewhilepointingitatvariousobjects.

MylarKaleidoscope

1. Foldtheindexcardintothreeequalpiecesinordertomakeitatriangulartube.2. MakesureyourMylaristhesamesizeaseachfoldofthetube.Trimasneeded.3. GluetheMylardowntothecardboard.4. Foldyourtubeagain,justmakingsurethattheedgesareascrispaspossible.5. Tapelengthwisealongthetopedgeofyourtriangulartube.6. Ifyouaremakingbothkaleidoscopes,comparethereflectionsyouseeinthislongertubewiththoseyou

sawinthemirrorkaleidoscope.

KaleidoscopeDataTable

NumberofMirrorsUsed

TypeofMirror(MylarorGlass,FlatorCurved,ShapeandSize)

HowweretheMirrorsArranged?(Triangle,Square…)

EffectonImage(Whatdiditlook

like?)

Reading

Acandleisalightsource(orsourceoflightwaves).Soareacampfire,alightbulb,andthesun.Anapple,however,reflectslight.Itdoesn’tgiveoffanylightonitsown,butyoucanseeitbecauselightbouncesofftheappleintoyoureye.Ifyoushutoffthelight,youcan’tseetheapple.Inthissameway,thesunisalightsource,andthemoonisalightreflector.

Lightcanbereflectedoffthesurfaceofdifferentmaterials.Theincidentangleofthelight(theanglethelighthitsthematerial)isalwaysthesameasthereflectedangleoflight.We’regoingtobuildakaleidoscopethatusesmirrorstoreflectlight.

Kaleidoscopesuselightfromasource,suchasthelightsinyourroomorthesuninthesky,andreflectthelightbacktooureyes.ThereflectionsbouncingallaroundonthemirrorsorMylarmakeinterestingshapesforoureyestosee.

Therearemanyvariationsforthisexperiment.YoucandoboththemirrorandMylarkaleidoscopes,orsimplychooseonethatworksbestwiththematerialsyou’reabletofind.FortheMirrorKaleidoscope,you’llfindthatifyouuseonlytwomirrors,you’llgetasolidbackground.Addathirdmirrorandtilttogetherintoatriangle(asshowninthevideo)andyou’llgettheentirefieldfilledwiththepattern.Youcanplacetransparentobjectsattheend(likemarblesfloatinginwaterormineraloil)orjustleaveitopenandpointatthenightstars.Bychangingthesizeandshapeofthemirrors,youcanchangethedimensionaleffectyousee.Justbesuretolookatthemirrorsurface,nottheopening.Youcanalsomakemirrorswideratthebottomandnarroweratthetop(thisiseasiertodowiththeMylar‐cardboardmirrors).Usefourorfivemirrorsinsteadofthreeindifferentcombinationstogetdifferenteffects.YoucanalsochangethelengthofthemirrorsorusecurvedmirrorsinsteadofflatbyliningtheinsideofanoatmealboxwithMylar.

Exercises

1. Whatisalightsource?

2. Whatisalightreflector?

3. Sketchanimageofsomethinginterestingthatyouwereabletoseeasthelightreflectedfromthemultiplesurfacesofthekaleidoscopetoyoureyes:

Lesson#3:LiquidPrism

Overview:Aprismun‐mixeslightbackintoitsoriginalcolorsofred,green,andblue.Inthisexperiment,waterisourprism.Youcanmakeprismsoutofglass,plastic,water,oil,oranythingelseyoucanthinkofthatallowslighttozipthrough.

WhattoLearn:Todayyou’regoingtoplaywithsplittingapartwhitelightintoitsprimarycolors.Thecoloroflightstrikinganobjectaffectshowoureyesseeit.

Materials

mirror shallowbakingdish sunlight indexcard

You’llalsohaveoneofthefollowing:

plainwater babyoilormineraloil waterwithonetablespoonofsaltmixedin distilledwhitevinegar isopropylrubbingalcohol clearliquidsoap(donotmixwithwater)

Experiment

1. Setatrayofliquidinsunlight.Ifyou’reusingwater,thenfillyourtraywithwater.Ifyou’reusingsalt,mixatablespoonofsaltintothewaterandthensetitinsunlight.Ifyou’reusinganythingelse,fillitwithyourliquidandsetitoutside.

2. Leanamirroragainsttheinsideedgeofthetrayandadjustitsothatarainbowappears.3. Usetheindexcard(oranotherwhitesurface)sothatyoucanclearlyseethereflectionfromyourprism.4. Youcanalsousealightbulbasanalternatelightsourcebyshiningitthroughaslitinaflatcardboard

surface.However,you’llfindthatsunlightismuchmoreeffectiveandwillmakeabrighter,morecompleterainbow.

5. Troubleshooting:Thisisoneoftheeasiestexperimentstodo,andthemostbeautiful.Thetroubleis,youdon’tknowwherethewatershadowwillshowup,somakesureyoupointthemirrortotheskyandplaywiththeangleofthemirroruntilyoufindthewaveringrainbow.Ifyoustillhavetrouble,usealargesheetofwhitepaperinsteadofthetinyindexcard.

LiquidPrismDataTable

TypeofLiquidforthePrism

Whatdidyouobserve?

Reading

Whatisaprism?Thinkofabeamoflight.Itzoomsfastonastraightpath,untilithitssomething,likeawaterdrop.Asthelightgoesthroughthewaterdrop,itchangesspeed.Thisiscalledrefraction,whichwewilldiscussmoreinafuturelesson.Thespeedchangedependsontheangleatwhichthelighthitsthewater,andwhatthedropismadeof.Ifitwasadropofmineraloil,thelightwouldslowdownabitmorebecausethefluidhasmoreopticaldensity.Sowhenwhitelightpassesthroughaprism,likethatwaterdrop,itchangesspeed,whichwecanseewithoureyesbecauseitalsoturnscolors.

Prismsun‐mixlightintoitsdifferentwavelengths.Whenlighthitstheprism,mostofitpassesthrough,althoughasmallbitoflightdoesgetreflectedoffthesurface,butwhenitpassesthroughitchangesspeed.Sincethesunlightismadeupofmanydifferentwavelengths(colors),eachcolorgetsbentbydifferentamounts,andyouseearainbowouttheotherside.Aslongasthelighttravelsatthesamespeed(likethroughtheair),it’swhite.Butassoonasthelighthitsthewaterandbendsatdifferentangles,thewavelengthsseparateandspreadout,makingtherainbowyousee.

Troubleshooting:Thisisoneoftheeasiestexperimentstodo,andthemostbeautiful.Thetroubleis,youdon’tknowwherethewatershadowwillshowup,somakesureyoupointthemirrortotheskyandplaywiththeangleofthemirroruntilyoufindthewaveringrainbow.Becausetheshadowisconstantlymoving,youcansnapafewpictureswhenyou’vegotitsoyoucanlookoverthefinerdetailslater.Ifthisprojectstilleludesyou,takealargesheetanduseitinsteadofthetinyindexcard.

Exercises

1. Whatservesastheprisminthisexperiment?

2. Whatpropertycanhelpmakesomethingagoodprismmaterial?

3. Whataresomeotheritemsthatcouldbeusedasprisms?

Lesson#4:LunarPhases

Overview:TheMoonappearstochangeinthesky.Onemomentit’sabigwhitecircle,andnextweekit’sshapedlikeasidewaysbikehelmet.There’sevenadaywhereitdisappearsaltogether.Sowhatgives?

WhattoLearn:ThesunilluminateshalfoftheMoonallthetime.Imagineshiningaflashlightonabeachball.Thehalfthatfacesthelightislitup.There’snolightonthefarside,right?FortheMoon,whichhalfislitupdependsontherotationoftheMoon.AndwhichpartoftheilluminatedsidewecanseedependsonwherewearewhenlookingattheMoon.Soundcomplicated?Thislabwillstraighteneverythingoutsoitmakessense.

Materials

ball flashlight

Experiment

1. Assignonepersontobethesunandhandthemtheflashlight.Staystandingupaboutfourfeetawayfromthegroup.Thesundoesn’tmoveatallforthisactivity.

2. AssignonepersontobetheMoonandhandthemtheball.Staystandingup,asyou’llbecirclingtheEarth.3. TherestofthepeoplearetheEarth,andtheysitrightinthemiddle(sotheydon’tgetaflashlightintheir

eyesastheMoonorbits).4. StartwithanewMoon.ShinetheflashlightabovetheheadsoftheEarth.MovetheMoon(ball)intoposition

sothattheballblocksallthelightfromtheflashlight.AsktheEarthkidshowmuchlighttheycanseeontheirsideoftheMoon(shouldbenone).WhichphaseoftheMoonisthis?__________________________________________________________________

5. NowtheMoonmovesaroundtotheoppositesideoftheEarthsothattheEarthkidscanseetheentirehalfoftheballlitupbytheflashlight.AsktheEarthkidshowmuchlighttheycanseeontheirsideoftheMoon(shouldbehalftheball).WhichphaseoftheMoonisthis?

__________________________________________________________________

6. Nowfindthepositionsforfirstquarter.WheredoestheMoonneedtostandsothattheEarthkidscanseethefirstquarterMoon?

7. Continuearoundinacompletecircleandfilloutthediagram.ColorinthecirclestoindicatethedarkhalfoftheMoon.Forexample,thenewMoonshouldbecompletelydarkened.

LunarPhasesDataObservations

1. Nowit’stimetoinvestigatewhyVenusandMercuryhavephases.PutthesuninthecenterandassignastudenttobeVenus.Venusgetstheball.

2. Venusshouldbewalkingslowlyaroundthesun.ThesunisgoingtohavetorotatetoalwaysfaceVenus,sincethesunnormallygivesofflightineverydirection.

3. TheEarthkidsneedtomovefurtheroutfromthesunthanVenus,sotheywillbewatchingVenusorbitthesunfromadistanceofacoupleoffeet.

4. Earthkids:whatdoyounoticeabouthowthesunlightsupVenusfromyourpointofview?IsthereatimewhenyougettoseeVenuscompletelyilluminated,andothertimeswhenit’scompletelydark?

5. Drawadiagramofwhat’sgoingon,labelingVenus’sfullphase,newphase,halfphases,crescent,andgibbousphases.Labelthesun,Earth,andall8phasesofVenuslikewedidontheboardfortheEarthatthebeginningofthislesson:

Reading

ThesunilluminateshalfoftheMoonallthetime.Imagineshiningaflashlightonabeachball.Thehalfthatfacesthelightislitup.There’snolightonthefarside,right?SofortheMoon,whichhalfislitupdependsontherotationoftheMoon.AndwhichpartoftheilluminatedsidewecanseedependsonwherewearewhenlookingattheMoon.Soundcomplicated?Thislabwillstraighteneverythingoutsoitmakessense.

Onequestionyou’llhearis:Whydon’twehaveeclipseseverymonthwhenthere’sanewMoon?Goodquestion.TheMoon’sorbitaroundtheEarthisnotinthesameplaneastheEarth’sorbitaroundthesun(calledtheecliptic).It’sactuallyoffbyabout5°.Infact,onlytwicepermonthdoestheMoonpassthroughtheecliptic.

Thelunarcycleisapproximately28days.Tobeexact,ittakesonaverage29.53days(29days,12hours,44minutes)betweentwofullmoons.Theaveragecalendarmonthis1/12ofayear,whichis30.44days.SincetheMoon’sphasesrepeatevery29.53days,theydon’tquitematchup.That’swhyonMoonphasecalendars,you’llseeaskippeddaytoaccountforthemismatch.

AsecondfullMooninthesamemonthiscalledablueMoon.It’salsoablueMoonifit’sthethirdfullMoonoutoffourinathree‐monthseason,whichhappensonceeverytwoorthreeyears.

TheMoonisn’ttheonlyobjectthathasphases.MercuryandVenusundergophasesbecausetheyareclosertothesunthantheEarth.IfwelivedonMars,thentheEarthwouldalsohavephases.

Exercises

1. DoesthesunalwayslightuphalftheMoon?

2. HowmanyphasesdoestheMoonhave?

3. WhatisitcalledwhentheMoonappearstogrow?

4. WhatisitcalledwhenyouseemorelightthandarkontheMoon?

5. Howlongdoesittakeforacompletelunarcycle?

Lesson#5:SkyinaJar

Overview:Haveyoueverwonderedwhytheskyisblue?Orwhythesunsetisred?Orwhatcoloroursunsetwouldbeifwehadabluegiantinsteadofawhitestar?Thislabwillanswerthosequestionsbyshowinghowlightisscatteredbytheatmosphere.

WhattoLearn:Particlesintheatmospheredeterminethecoloroftheplanetandthecolorsweseeonitssurface.Thecolorofthestaralsoaffectsthecolorofthesunsetandoftheplanet.Thecoloroflightstrikinganobjectaffectshowoureyesseeit.

Materials

glassjar flashlight fingernailpolish(red,yellow,green,blue) cleartape water darkroom fewdropsofmilk

Experiment

1. Makeyourroomasdarkaspossibleforthisexperimenttowork.2. Makesureyourlabelisremovedfromtheglassjaroryouwon’tbeabletoseewhat’sgoingon.3. Filltheclearglassjarwithwater.4. Addateaspoonortwoofmilk(orcornstarch)andswirl.5. Shinetheflashlightdownfromthetopandlookfromtheside–thewatershouldhaveabluishhue.The

smallmilkdropletsscatterthelightthesamewayouratmosphere’sdustparticlesscattersunlight.6. Tryshiningthelightupfromthebase–wheredoyouneedtolookinordertoseeafaintred/pinktint?If

not,it’sbecauseyouarelookingforhuesthatmatchourrealatmosphere,andthejarjustisn’tthatbig,norisyourflashlightstrongenough!Instead,lookforaveryslightcolorshift.Ifyoudothisexperimentafterbeinginthedarkforabout10minutes(lettingyoureyesadjusttothelackoflight),itiseasiertoseethesubtlecolorchanges.Justbecarefulthatyoudon’tletthebrilliantflashlightruinyournewlyacquirednight‐vision,oryou’llhavetostartthe10minutesalloveragain.

7. Ifyouarestillhavingtroubleseeingthecolorchanges,shineyourlightthroughthejarandontoanindexcardontheotherside.Youshouldseeslightcolorchangesonthewhitecard.

8. Covertheflashlightlenswithcleartape.9. Paintonthetape(notthelens)thefingernailpolishyouneedtocompletethetable.10. Repeatsteps7‐9andrecordyourdata.

SkyinaJarDataTable

FlashlightColor Location Color(s)

White Sideofjar

White BottomofJar

Red Sideofjar

Red BottomofJar

Yellow Sideofjar

Yellow BottomofJar

Green Sideofjar

Green BottomofJar

Blue Sideofjar

Blue BottomofJar

Reading

Whyisthesunsetred?Thecolorsyouseeintheskydependonhowlightbouncesaround.Thered/orangecolorsofsunsetandsunrisehappenbecauseofthelowanglethesunmakeswiththeatmosphere,skippingthelightoffdustanddirt(nottomentionsolidaerosols,soot,andsmog).Sunsetsareusuallymorespectacularthansunrises,asmore“stuff”floatsaroundattheendoftheday(therearelessparticlespresentinthemornings).Sometimesjustaftersunset,agreenflashcanbeseenejectingfromthesettingsun.

TheEarthappearsbluetotheastronautsinspacebecausetheshorter,fasterwavelengthsarereflectedofftheupperatmosphere.Thesunsetsappearredbecausetheslower,longerwavelengthsbounceofftheclouds.

Sunsetsonotherplanetsaredifferentbecausetheyarefarther(orcloser)tothesun,andalsobecausetheyhaveadifferentatmospherethanplanetEarth.TheimageshownhereisasunsetonMars.

Exercises

1. Whatcolorsdoesthesunsetgothrough?

2. Doesthecolorofthelightsourcematter?

Lesson#6:LightTricks

Overview:Todayyougettoseethesciencebehindtheillusionbylearninghowlightstrikinganobjectaffectshowoureyesseeit.

WhattoLearn:Lightcanbebentwhenitpassesthroughmaterials.Theamountthatthelightbendsiscalledtheindexofrefraction.Howmuchlightbendsdependsonthematerialit’spassingthrough.Thisqualityismeasuredforeachindividualmaterialandiscalledtheopticaldensity.Themoredensethesubstance,theslowerthelighttravelsthroughit,andthemorethelightbends.

Materials

glassjar penny laser(optional) flashlight milkorflour

LightTricksDataTable

Whenyoudothepencilillusiontrick,recordyourobservations.

WaterLevel: WaterLevel: WaterLevel:

Experiment

1. Recordyourobservationsonthedatasheetandintheexercisesasyougo.2. Tossonecoinintoawaterglassandfillwithaninchofwater.Holdtheglassupandfindwhereyouneedto

looktoseeTWOcoins.3. Lookthroughthetopoftheglass–howmanycoinsaretherenow?Whataboutwhenyoulookfromthe

side?4. Tossinasecondcoin–nowhowmanyarethere?5. Removethecoinsandturnoutthelights.Shineaflashlightbeamthroughtheglassontoanearbywall.

(Hint–ifthisdoesn’twork,tryusingasquareclearcontainer.)Stickapieceofpaperonthewallwhereyourlightbeamisandoutlinethebeamwithapencil.

6. Shinethelightatanangleupthroughthewatersothatitbouncesoffthesurfaceofthewaterfromunderneath.Traceyournewoutlineandcompare…aretheyboththesameshape?

7. Addateaspoonofmilkandstirgently.(Nomilk?Trysprinklinginabitofwhiteflour.)Nowshineyourflashlightthroughthecontainerasyoudidinsteps4and5andnoticehowthebeamlooks.

8. Usearoundcontainerinsteadofsquare…what’sthedifference?

Reading

Haveyoueverbrokenapencilbystickingitintoaglassofwater?Thepencilisn’treallybroken,butitsurelookslikeit!What’sgoingon?Lightcanbebentwhenitpassesthroughmaterials.Theamountthatthelightbendsiscalledtheindexofrefraction.Howmuchlightbendsdependsonthematerialit’spassingthrough.Thisqualityismeasuredforeachindividualmaterialandiscalledtheopticaldensity.Themoredensethesubstance,theslowerthelighttravelsthroughit,andthemorethelightbends.Tobeexact,whenabeamoflighthitsadifferentsubstance(likemovingfromairtowater),thewavelengthchangesbecausethespeedofthelightchanges.Ifyou’rethinkingthatthespeedoflightisalwaysconstant,you’reright…inouterspace,lighttravelsat186,000milespersecond.ButtheEarthiscoveredwithanatmosphere,andassoonasthelightpassesintothisthickcloudofnitrogenandoxygengas,itslowsdownabit.Thespeedoflightchangeswheneveritpassesfromonematerialtoanother,likewhenitmovesfromwatertoice,ortosunglasses,smoke,fog,orwindows.Howmuchthelightspeedslowsdowndependsonwhatthematerialismadeof.Mineraloilandwindowglasswillslowlightdownmorethanwater,butnotasmuchasdiamondsdo.Exercises

1. Whenonecoinisinthewater,youcanactuallyseetwo:Arethecoinsboththesamesize?Whichoneistheoriginalcoin?

2. Instep2oftheexperiment:Howmanycoinsaretherewhenviewedfromthetopoftheglass?Whataboutwhenyoulookfromtheside?

3. Whathappenedwhenyoutossedinasecondcoin?

4. Howdidyouroutlinescompare?

Lesson#7:BlackLightTreasureHunt

Overview:EvernoticehowBRIGHTyourwhiteT‐shirtlooksindirectsun?That’sbecausemomwashedwithfluorescentlaundrysoap(nokidding!).ThesoapmanufacturersputindyesthatglowwhiteunderaUVlight,whichmakeyourclothesappearwhiterthantheyreallyare.

WhattoLearn:Lightcanbeabsorbedandretransmittedinadifferentcolor,dependingonhowthelightstrikestheobjectandtheamountofenergythelightinitiallyhas.

Materials

UVblackfluorescentlight darkeveninginsideyourhouse

Experiment

1. TurnoffallthelightsinyourhouseandturnonyourUVblacklight.2. Findthingsthatglowbothinsideandoutsidethehouse.3. Whatfluorescesinyourhouse?Herearesomethingstotry:whitepaper(althoughpapermadepre‐1950

doesn’t,whichishowinvestigatorstellthedifferencebetweenoriginalsandfakes),clubsodaortonicwater(it’sthequininethatglowsblue),bodyfluids(yes,blood,urine,andmoreareallfluorescent),Vitamins(VitaminA,B,B‐12(crushanddissolveinvinegarfirst),thiamine,niacin,andriboflavinarestronglyfluorescent),chlorophyll(grindspinachinasmallamountofalcohol(likeethylalcohol)andpouritthroughacoffeefiltertogettheextract(keepthesolidsinthefilter,nottheliquid)),antifreeze,laundrydetergents,toothwhiteners,postagestamps,driver’slicense,jellyfish,andcertainrocks(fluorite,calcite,gypsum,ruby,talc,opal,agate,quartz,amber)andtheHopeDiamond(whichisblueinregularlight,butglowsred).

4. Completethedatatable.

BlackLightTreasureHuntDataTable

Item/Object Whatcolordiditglow?

Reading

Lightbulbsuseincandescence,whichmeansthatthelittlewire(whichismadefromtheelementtungsten)getssohotwhenyouswitchitonthatitgivesoffheatandlight.Unfortunately,thesebulbsgiveoffalotofheat,whichyou’llnoticeifyoubringyourhandclosetoitafterit’sbeenonforawhile.Incandescencehappenswhenyourelectricstoveglowscherryred‐hotandyoucanvisiblyseethelightenergy.Oursungivesoffenergythroughincandescencealso–alotofit.

Ontheotherendofthings,coldlightreferstothelightfromaglowstick,calledluminescence.Achemicalreaction(chemiluminescence)startsbetweentwoliquids,andtheenergyisreleasedintheformoflight.Ontheatomicscale,theenergyfromthereactionbumpstheelectrontoahighershell,andwhenitrelaxesbackdownitemitsaphotonoflight.Phosphorescenctlightistheglow‐in‐the‐darkkindoflightyouseeafteryouchargeupaglowtoywithabrightlightsource.Thisdelayedafterglowhappensbecausewhenyouchargedtheobjectwithlight,thelightactuallyhitstheatom’selectronandwhacksitintoahigherenergystate.Whentheelectronrelaxesbackdownitslowerenergystate,itemitsalightparticleof(usually)adifferentwavelength(color).That’swhyglow‐in‐the‐darktoysareoftenadifferentcolorthanthelighttheyemitafterchargedup.Sincelightisaformofenergy,theninorderforthingstoglowinthedark,youhavetoaddenergyfirst.Triboluminescenceisthesparkyouseewhenyousmacktwoquartzcrystalstogetherinthedark.Othermineralssparkwhenstrucktogether,butyoudon’thavetobearockhoundtoseethisoneinaction–justtakeaWint‐O‐GreenLifesaverinadarkclosetwithamirrorandyou’llgetyourownsparkshow.Ifyouchewthecandywithyourmouthopen,you’llbeabletoseethesparksinyourmouthwithamirror.Thesparkisbasicallylightfromfriction.Fluorescenceissimilartophosphorescence,exceptthatitrequiresacontinuallightsourceinordertoglow.Thesetypesofpaintsarepopularwithdarkamusement‐parkrides.Ifyoulookcarefully,you’llseeUVlightshiddenallaroundtomaketheimagesglowasyouspeedthroughtheride.Innature,you’llfindfluorescenceincertainrocks,plantsandanimals.FluorescentobjectsabsorbtheUVlightandremitacompletelydifferentcolor.Likewithphosphorescence,thelightstrikestheelectronandbumpsitupalevel,andwhentheelectronrelaxedbackdown,emitsaphoton(lightparticle)ofadifferentwavelength.

Fluorescentlightsgiveoutlessheat,butmorelight.Sincetheydon’tloseasmuchenergytoheat,theyaremoreenergy‐efficient.Iwillusuallyholdupanincandescentbulbandafluorescentbulbandaskthestudentshoweachmakeslight.Afluorescenttubeislinedwithwhitestuffcalledphosphor,whichgivesofflightwheneverit’sstruckbyUVrays.ThetubeisfilledwithagasthatgivesoffUVrayswhenplacedinanelectricalfield.Whenthebulbisturnedon,electronsripthroughthetubeandgoouttheotherside.Astheygothrough,theysmackintothegasvaporwhichreleaseslightrays(UVinafluorescenttube)thathitthephosphorontheinsideofthetube,whichthenemitslight.Fluorescentlights,oranytubeofgasfromthenoblegasescolumnontheperiodictable,likeneon,willalsoglowinanelectricallychargedfield.

Phosphorescenceisatypeoffluorescencelikeyoufindinglowsticksandotherglow‐in‐the‐darkitems.

Triboluminescenceisatypeoffluorescentlightthatcomesfromfriction,likewhenstrikingtwoquartzcrystalstogether.(YoucanhandoutWint‐O‐GreenLifesaversaspartoftheirhomeworkforthedayandhavethemrecordtheirresultsintheirlab.)

Exercises

1. Whyareincandescentlightslessenergy‐efficientthanfluorescentlights?

2. Whatarethetwotypesoffluorescentlights?

3. Whatkindsofthingsdidyoufindthatglowonyourtreasurehunt?Giveatleastfiveexamples.

Lesson#8:Benham’sDisk

Overview:CharlesBenham(1895)createdatoytoppaintedwithaspecificpattern.Whenyouspintheblackandwhitepattern,surprisingarcsofcolor(called“patterninducedflickercolors”)showup;andhere’stheoddpart:Differentpeopleseedifferentcolors!

WhattoLearn:Thecoloroflightstrikinganobjectaffectshowoureyesseeit.Theconesandrodsinsideoureyescollectimagesthataretransmittedtothebrain.

Materials

Benham’sDisksheet string(about3feet) 8indexcards gluestick

Experiment

1. CutouttheBenham’sDisks.2. Gluethediskstoindexcardsforstability.Regularpapertendstofloparoundwhenyouspinitquickly.3. Labeleachdiskwithanumberfrom1to6onthebacksidesoyoucanrecordyourobservationsinthedata

tablelater.4. Spinthedisksusingthemethodyouchoose.Playwiththisabitbeforeyoutakedatasoyoucanget

comfortablewithhowtodotheexperiment.5. Whenyouareready,recordyourobservationsinthedatatable.

Reading

Wecan’treallysaywhythiseffectwithBenham’sDiskhappens,butthereareafewinterestingtheories.Theretinaatthebackofyoureyehasabunchoflight‐sensitivecellscalledconesandrods.Youreyeballhastwodifferentwaysofseeinglight:conesandrods.Conesareusedforcolorvisionandforseeingbrightlight,andtherearethreetypesofcones(red,green,andblue).Rodsareimportantforseeinginlowlightandtheysenseblack,white,andgrayshades.Together,theyturnthelightthatentersyoureyeintoanimage.

Benham’sDiskDataTable

Disk# WhatColorsDidYouSee?

YourOwnDesign#1

YourOwnDesign#2

Exercises

1. Whatcolorswereyouabletoseewhenthediskswerespinning?

2. Howdidthedifferentpatternslookwhentheywerespun?

3. Howdidspeedanddirectionaffectwhatyousaw?

Benham’sDisks

Lesson#9:EyeBalloon

Overview:Inthislab,wearegoingtomakeaneyeballmodelusingaballoon.Thisexperimentshouldgiveyouabetterideaofhowyoureyeswork.Thewayyourbrainactuallyseesthingsisstillamystery,butusingtheballoonwecangetagoodworkingmodelofhowlightgetstoyourbrain.

WhattoLearn:Weseeobjectswhenlighttravelingfromanobjectentersoureye.

Materials

biconvexplasticlens

roundballoon,white,9inches

assistant

votivecandle

blackmarker

bookofmatches

Experiment

1. Blowuptheballoonuntilitisaboutthesizeofagrapefruit.Ifit’sdifficulttoinflate,stretchthematerialafewtimesoraskanadulttohelpyou.

2. Youwillneedanextrasetofhandsforthisportion.Askyourpartnertoholdtheneckoftheballoonclosedtokeeptheairinwhileyouinsertthelensintotheopening.Thelenswillneedtobeinsertedperpendiculartotheballoon’sneck.Itwillpreventanyairfromescapingonceit’sinplace.Likeyoureye,lightwillenterthroughthelensandtraveltowardthebackoftheballoon.

3. Holdtheballoonsothatthelensispointingtowardyou.Takethelensbetweenyourthumbandindexfinger.Lookintothelensintotheballoon.Youshouldhaveaclearviewoftheinside.Starttotwisttheballoonalittleandnoticethattheneckgetssmallerlikeyourpupilsdowhenexposedtolight.Practiceopeningandclosingtheballoon’s“pupil.”

4. Haveanadulthelpyouputthecandleonthetableandlightit.Turnoutthelights.5. Puttheballoonabout20to30centimetersawayfromthecandlewiththelenspointedtowardit.The

balloonshouldbebetweenyouandthecandle.Youshouldseeaprojectionofthecandle’sflameonthebackoftheballoon’ssurface.Movetheballoonbackandforthinordertobetterfocustheimageonthebackoftheballoonandthenproceedwithdatacollection.

6. Describetheimageyouseeonthebackoftheballoon.Howisitdifferentfromtheflameyouseewithyoureyes?Drawapictureofhowtheflamelooks.

7. Thefocallengthisthedistancefromtheflametotheimageontheballoon.Measurethisdistanceandrecordit.

8. Whathappensifyoulightlypushdownonthetopoftheballoon?Doesthisaffecttheimage?Youareexperimentingwiththeaffectcausedbynear‐sightedness.

9. Toapproximateafarsightedeye,gentlypushinthefrontandbackoftheballoontomakeittaller.Howdoesthischangewhatyousee?

EyeBalloonDataTable

Drawapictureofhowtheflamelookstoyou.

Recordthefocallengthfromflametotheimage.

Whathappenstotheimagewhenyoupushdownonthetopoftheballoon?

Whatdoyouseewhenyoupushonthefrontandbackoftheballoontomakeittaller?

Reading

First,we’lldiscussthepartsoftheballoonthatrelatetopartsofyoureye.Thewhiteportionoftheballoonrepresentsyoursclera,whichyoumayhavealreadyguessedisalsothewhitepartofyoureye.Itisactuallyacoatingmadeofproteinthatcoversthevariousmusclesinyoureyeandholdseverythingtogether.Ofcourse,thelensyouinsertedrepresentstheactuallensinyoureye.Themusclessurroundingthelensarecalledciliarymusclesandtheyarerepresentedbytherubberneckofyourballoon.Theciliarymuscleshelptocontroltheamountoflightenteringyoureyes.Theretinaisinthebackofyoureye,whichisrepresentedbytheinsidebackofyourballoon.Theretinasupportsyourrodsandcones.Theycollectinformationaboutlightandcolorandsendittoyourbrain.

Therearenolightreceptorsintheareaofyoureyewheretheopticnerveattachestoyoureyeball.Thisisyourblindspotandifanimageisinthisspot,thelightreflectedoffofitdoesn’tgetperceivedbyyoureye.

Thisisafunexperimenttoplaywithusingdifferentagesofpeople.Asfolksgetolder,theshapeoftheeyechangesandtheblindspotcanactuallychange.Askafewfellowadultstohelpyoudemonstratethelabandmeasurethedistancefortheblindspotbasedonhowoldtheadultsare.Youcanalsotesttoseeifdifferentpeoplewith

differentvisionhavedifferentblindspots.Forexample,istheblindspotthesameforsomeonewith20/20versus20/40?Orwithorwithouteyeglasses?Havefunwiththedifferentvariations!

Exercises

1. Howdoesyoureyeworklikeacamera?

2. Howcanyoutellifalensisdoubleconvex?

3. Whatisthedifferencebetweenconvexandconcave?

4. Canyougiveanexampleofaneverydayobjectthathasbothaconvexandaconcaveside?

5. Howcanyouchangetheballoontomakeitlikeanear‐sightedeye?

6. Howcanyouchangetheballoontomakeitlikeafar‐sightedeye?

Lesson#10:DisappearingFrogOverview:Youropticnervecanbethoughtofasadatacordthatispluggedintoeacheyeandconnectsthemtoyourbrain.Theareawherethenerveconnectstothebackofyoureyecreatesablindspot.Therearenoreceptorsinthisareaatallandifsomethingisinthatarea,youwon’tbeabletoseeit.Thisexperimentlocatesyourblindspot.WhattoLearn:Conesandrodsturnthelightthatenterstheeyeintoimagesthataretransmittedtothebrain.Oureyeshaveablindspotwheretheopticnerveconnectstothebackoftheeyebecausetherearenolightreceptorsthere.

Materials

froganddotprintout meterstick scrappieceofcardboard

Experiment

1. Printoutthefroganddotandremovethedottedportion.Attachittothepieceofcardboard,whichshouldhaveamatchingportionremoved.Youcanplacethepaperandcardboardonthemeterstickatthenotchedarea.

2. Nowtolocateblindspots.First,closeyourlefteye.Lookatthefrogwithyourrighteye.Canyouseethedotandthefrog?Youshouldbeabletoseebothatthispoint,butconcentrateonthefrog.Nowslowlymovethesticktowardyousothatthefrogiscomingtowardyoureye.Payattentionandstopwhenthedotdisappearsfromyourperipheralvision.Atthispoint,thelighthittingthedotandreflectingbacktowardyoureyeishittingtheblindspotatthebackofyourrighteyeball,soyoucan’tseeit.Recordhowfaryoureyeisfromthecardforyourrighteye.

3. Continuetomovethesticktowardyourface,andatsomepointyouwillnoticethatyouareabletoseethedotagain.Keepmovingthestickforwardandback.Whathappenstothedot?

4. Repeatsteps2and3withyourlefteye,keepingyourrighteyeclosed.Thistime,stareatthedotandwatchforthefrogtodisappear.Movethepaperonthestickbackandforthslowlyuntilyounoticethefrogdisappears.Youhavefoundtheblindspotforyourlefteye.Besuretonotethedistancethepaperisfromyoureye.

DisappearingFrogDataTable

StudentName RightorLeftEye? DistancefromEyetoFrog

Exercises

1. Whatdidyounoticeaboutthevisionofthestudentandtheblindspotthatyoumeasured?

2. Whydoyouthinkit’simportanttoknowwhereyourblindspotis?

Lesson#11:PinholeCamera

Overview:Todayyougettolearnhowtomakeasimplecamerausingequallysimplematerials.It’ssurprisinghowsharptheimagesappearwhenyoudothisexperiment!

WhattoLearn:Althoughthismightseemobvious,weseeobjectswhenlighttravelingfromanobjectentersoureye.Wecandetectlightinotherways(asyou’llfindoutinalaterlesson),buttheeyesdetectonlyvisiblelight.

Materials

box tracingpaper razororscissors tape tack meterstick

Experiment

1. Useacardboardboxthatislight‐proof(noleaksoflightanywhere).2. Seallightleakswithtapeifyouhaveto.Cutoffonesideofthebox(Note–there’snoneedtodothisif

you’reusingashoebox.)3. Tapeapieceoftracingpaperoverthecutoutside,keepingittautandsmooth.4. Makeapinholeintheboxsideoppositeofthetracingpaper.5. Pointthepinholeatasunnywindowandmovetowardorawayfromthewindowuntilyouseeitsimagein

clearfocusonthetracingpaper.6. Ifyouhaveamagnifyingglass,placeitinfrontofthepinholetohelpsharpentheimage.7. Completethedatatablebymeasuringyourcamerawiththemeterstick.

PinholeCameraDataTable

Measure: Length(inches,feet,cm,or…?)

Boxlength(thisisonedimensionofthescreen)

Boxwidth(thisistheotherscreendimension)

Boxheight(thisisthedistancefromtheholetothescreen)

Distancefromholetothewindow(orcandle)whenfocused

Drawadiagramofyourexperiment,labelingthedifferentpartsanddistancesmeasuredfromabove:

Reading

Lighttravelsinastraightline;itcomesthroughthewindowandintotheholeinyourcamera.Theraysoflightcrossastheyenterthetinyhole,creatinganinvertedimagethatyouseeprojectedonthescreen.Thebiggestproblemwiththiscameraisthattheinletholeissotinythatitletsinsuchasmallamountoflightandmakesafaintimage.Ifyoumaketheholelarger,yougetabrighterimage,butit’smuchlessfocused.Themorelightrayscomingthrough,themoretheyspreadouttheimageandcreateafuzzierpicture.You’llneedtoplaywiththesizeoftheholetogetthebestimage.Youcanalsolightasinglecandleinthemiddleoftheroom(insteadofusingabrightwindow)forthekidstousetheircamera.Justbecarefultheydon’tgettooclose–thecamerasareflammable!Youcanletyourstudentsgocrazytakingactualphotoswiththiscamerabystickingonapieceofundevelopedblackandwhitefilm(useamoderatelyfastASAratingifyoucanstillfindit),butIrecommendusingtracingpaperandasetofeyeballstoviewyourimages.OPTIONAL:Youcanholdupamagnifyingglassinfrontofthepinholetosharpentheimage.

Exercises

1. Howdotheimagesappearwhenthey’reprojectedontothepaperinsideyourcamera?

2. Whydoyouthinkit’simportanttomaketheboxaslight‐proofaspossible?

3. Isthereapartofyourbodythatworkssimilarlytothepinhole?

4. Sketchapictureofsomethingyousawthroughyourpinholecamera.

Lesson#12:Diffraction

Overview:Whenlightpassesthroughdiffractiongratings,itsplits(diffracts)thelightintoseveralbeamstravelingatdifferentdirections.Ifyou'veeverseenthe“iridescence”ofasoapbubble,aninsectshell,oronapearl,you'veseennature'sdiffractiongratings.

WhattoLearn:Everplaywithaprism?Whensunlightstrikestheprism,itgetssplitintoarainbowofcolors.Prismsun‐mixthelightintoitsdifferentwavelengths(whichyouseeasdifferentcolors).Diffractiongratingsaretinyprismsstackedtogether.Thedirectionthatthebeamgetssplitanddiffracteddependsonthespacingofthediffractiongratingandalsothewavelengthoftheincominglight.

Materials

feather CDorDVD diffractiongrating

Experiment

1. Takeafeatherandputitoveraneye.2. Stareatalightsourcethroughthefeather,likeanincandescentlight.3. YoushouldseetwoorthreelightsandarainbowX.4. AimtheCDsothelighthitstheCDandmakesrainbows.5. Lookatthelightsourcethroughthediffractiongrating.6. Drawwhatyouseeforallthree.Weretheythesame?7. Takethisona“lighttreasurehunt”tofinddifferentlightsources.Goodchoicesarecandles,incandescent

bulbs,fluorescentbulbs,nonsigns,halogenlamps,streetlights,stoplights,andanythingelseyoucanthinkofthatgivesofflight(exceptthesun).

8. Completethetableasyouviewthedifferentlightsourcesthroughyourdiffractiongratings.

DiffractionDataTable

LightSource DiffractiveObject(Feather,CD,orGrating?)

DrawWhatYouSee:

Reading

Everplaywithaprism?Whensunlightstrikestheprism,itgetssplitintoarainbowofcolors.Prismsun‐mixthelightintoitsdifferentwavelengths(whichyouseeasdifferentcolors).Diffractiongratingsaretinyprismsstackedtogether.Thedirectionthatthebeamgetssplitanddiffracteddependsonthespacingofthediffractiongratingandalsothewavelengthoftheincominglight.

Thefeatherworksbecausetherearetiny“hairs”onthefeatherthatareactingliketinyprisms.

DiffractiongratingswerefirstdiscoveredbyJamesGregory,rightaroundthetimeNewtonperformedhisfamousprismexperimentswithbirdfeathers.Thefirstdiffractiongratingstookalongtimetoconstruct,astheywereindividualhairsstrungbetweenscrews.

Adiffractiongratingbendsthelightandsplitsitintodifferentbeams.Youcanseethisverywellwhenyouuseamonochromaticlightsource,likealaser,insteadofamulti‐wavelengthlightsource.

Exercises

1. Whichlightsourcegavethemostinterestingresults?

2. Whathappenswhenyouaimalaserbeamthroughthediffractiongrating?

3. HowisaCDdifferentandthesameasadiffractiongrating?

4. Whydoesthefeatherwork?

Lesson#13:SpeedofLight

Overview:Oneofthebiggestchallengeswithmeasuringthespeedoflightisthatthephotonsmovefast,toofasttowatchwithoureyeballs.Soinstead,we’regoingtowatchtheeffectsofmicrowavelightandbaseourmeasurementsontheeffectsthelighthasondifferentkindsoffood.

WhattoLearn:Todayyougettothinkandactlikearealscientistbydoinganexperiment,takingmeasurements,usingmathtofigureoutananswer,andtestdifferentmaterialstoseewhichgivesyouthebestresult.

Materials

chocolatebar(extra‐largebarsworkbest) minimarshmallows chocolatechips Americanslicedcheese(thekindthatcomesindividuallywrapped) paperplates ruler calculator pencilandpaper microwave(You’llonlyneedoneofthesefortheentiregroup.)

Experiment

1. First,you’llneedtofindthe“hotspots”inyourmicrowave.Thevideowilldemonstratethisforyou,butherearethesteps:

2. Removetheturntablefromyourmicrowaveandplaceanakedbarofchocolateonaplateinsidethemicrowave.(MakesurethechocolatebaristheBIGsize–you’llneedatleast7inchesofchocolateforthistowork.)

3. Turnthemicrowaveonandwaitafewminutesuntilyouseesmallpartsofthechocolatebarstarttobubbleup,andthenquicklyopenthedoor(itwillstarttosmokeifyouleaveitintoolong).

4. Lookcarefullyatthechocolatebarwithouttouchingthesurface…youarelookingforTWOhotspots,notjustone–theywilllooklikesmallvolcanoeruptionsonthesurfaceofthebar.

5. Ifyoudon’thavetwo,grabafreshplate(youcanreusethechocolatebar)andtryagain,changingthelocationoftheplateinsidethemicrowave.You’relookingfortheplacewherethemicrowavelighthitsthechocolatebarintwospotssoyoucanmeasurethedistancebetweenthespots.

6. Openupthedoororlookonthebackofyourmicrowaveforthetechnicalspecifications.You’relookingforafrequencyinthe2,000‐3,000MHzrange,usuallyabout2450MHz.Writethisnumberdownonasheetofpaper–thistellsyouthemicrowaveradiationfrequencythattheovenproduces,andwillbeusedforcalculatingthespeedoflight.

7. Whenyou’rereadytotakeameasurement,popinthefirstfoodtypeonaplate(withouttheturntable!)intothebestspotinthemicrowave,andturniton.Removewhenbothhotspotsform,andbeingcarefulnottotouchthesurfaceofthefood,measurethecenter‐to‐centerdistanceusingyourrulerincentimeters.TIP:Ifyou’reusingmini‐marshmallowsorchocolatechips(orothersmallerfoods),you’llneedtospreadthemoutinanevenlayeronyourplatesoyoudon’tmissaspotthatcouldbeyourhotspot!

8. Notethatwhenyoumeasurethedistancebetweenthehotspots,youareonlymeasuringthepeak‐to‐peakdistanceofthewave…whichmeansyou’reonlymeasuringhalfofthewave.We’llmultiplythisnumberby

twotogettheactuallengthofthewave(wavelength).Ifyou’reusingcentimeters,you’llalsoneedtoconvertthosetometersbydividingby100.

9. So,ifyoumeasure6.2cmbetweenyourhotspots,andyouwanttocalculatethespeedoflightandcomparetothepublishedvaluewhichisinmeterspersecond,here’swhatyoudo:2,450MHzisreally2,450,000,000Hzor2,450,000,000cyclesper1second

10. Findthelengthofthewave(incm):2*6.2cm=(12.4cm)/(100cm/m)=0.124meters11. Multiplythewavelengthbythemicrowaveovenfrequency:

0.124m*2,450,000,000Hz=303,800,000m/s12. Thepublishedvalueforlightspeedis299,792,458m/s=186,000miles/second=671,000,000mph13. Calculate%Differencebyusingthissimpleformula:

%Diff=|MeasuredValue–PublishedValue|÷PublishedValuex100

SpeedofLightDataTable

FoodType HotspotDistance(cm)

CalculatedSpeedofLight(m/s)

%Difference

Graphing:Usethedatafromyourtabletomakeagraphofyourresults,puttingthedifferenttypesoffoodontheverticalaxisandthemeasured(calculated)speedoflightvalueonthehorizontalaxis.Refertothesamplewhileyoucreateyourown.Inthegraphsample,notethat“3.00E+08”means3witheightzerosafterit,or300,000,000meterspersecond.

Reading

Whenyouwarmupleftovers,haveyoueverwonderedwhythemicrowaveheatsthefoodandnottheplate?(Well,someplates,anyway).Ithastodowiththewaymicrowaveovenswork.

Microwaveovensusedielectricheating(orhighfrequencyheating)toheatyourfood.Basically,themicrowaveovenshootslightbeamsthataretunedtoexcitethewatermolecule.Foodsthatcontainwaterwillstepupanotchinenergylevelsasheat.(Themicrowaveradiationcanalsoexciteotherpolarizedmoleculesinadditiontothewatermolecule,whichiswhysomeplatesalsogethot.)

Oneofthebiggestchallengeswithmeasuringthespeedoflightisthatthephotonsmovefast,toofasttowatchwithoureyeballs.Soinstead,we’regoingtowatchtheeffectsofmicrowavelightandbaseourmeasurementsontheeffectsthelighthasondifferentkindsoffood.Microwavesuselightwithawavelengthof0.01to10cm(that’sthe”microwave”partoftheelectromagneticspectrum).Whendesigningyourexperiment,you’llneedtopaycloseattentiontothefinerdetailssuchasthefrequencyofyourmicrowaveoven(foundinsidethedoor),whereyouplaceyourfoodinsidetheoven,andhowlongyouleaveitinfor.

0.00E+00 1.00E+08 2.00E+08 3.00E+08 4.00E+08

Hershey's milk chocolate

Two raw eggs, beaten

Marshmallows (big)

Chocolate chips

Buttered bread

Cheese on crackers

Hershey's dark chocolate

Hershey's white chocolate

Mini‐marshmallows

Published Value: Speed of Light

Speed of Light (m/s)

Material Typ

eSAMPLE GRAPH: Measuring the Speed of Light

Lesson#14:MixingColors

Overview:Therearetwodifferentsetsofprimarycolors.Thethreeprimarycolorsoflightarered,green,andblue.However,thethreecolorsthatartistsusearered,yellow,andblue.Whathappensifyoumixred,green,andbluepaint?

WhattoLearn:Thethreeprimarycolorsoflightarered,blue,andgreen.Redandgreenlightmixedtogethermakeyellowlight.

Materials

scissors crayonsORmarkers sharpenedwoodpencilORskewer indexcards cup drill(optional)

Experiment

1. Stacktheindexcards2. Usethecuptotraceacircleonthetopcard.3. Keepthecardsstackedwhileyoucutoutthecircles.Theydon’thavetobeperfect,butmakesureallthe

sharpcornersarecutoff.4. Usingdifferentcolormarkers,makedifferentcoloredslices(orpiepieces)oneachcircle.Thesearethe

colorsthatwillblurtogetherinyourexperiment.5. Pokeaholethroughthecenterofthenow‐colorfulcirclewithyourpencilorskewer.Makesurethecolored

sideisfacinguptowardyou,notdowntowardthetable.6. Tospinthislikeatop,makethe“okay”symbolwithyourindexfingerandthumb.Puttheskewerinside

thecircleyourfingersmakeandspinit.Yourhandwillhelptokeepthetopuprightsothatyouareabletoseehowthecolorsblendtogether.

7. Optionally,anadultcanhelpyouuseadrill,handheldmixer,orelectricscrewdrivertospinthecirclemuchfasterforamorenoticeableeffect.

MixingColorsDataTable

ColorandPercentage

Result

Example:blue50%

Example:red50%

Example:(nothinghere‐somecellsmaybeblank)

Example:purple

Reading

Mostkidsunderstandhowyellowpaintandbluepaintmakegreenpaint,butaretotallystumpedwhenredlightandgreenlightmixtomakeyellowlight.Thedifferenceisthatwe’remixinglight,notpaint.Lotsofsciencetextbooksstillhavethisexperimentlistedunderhowtomixlight:“Stirtogetheroneofredwaterandoneglassofgreenwater(dyedwithfoodcoloring)togetaglassofyellowwater.”Hmmm…theresultIgetisayuckygreenish‐browncolor.Whathappened?Thereasonyoucan’tmixgreenandredwatertogetyellowisthatyou’reessentiallystillmixingpaint,notlight.Butdon’ttakeourwordforit–testitoutforyourselfwiththissuper‐fastlightexperimentonmixingcolors.Exercises

1. Whathappenswhenblueandredaremixedonthespinner?

2. Whathappenswhenredandgreenaremixedonthespinner?

3. Whatcolorswouldyoumixtogetorange?

4. Whataretheprimarycolorsoflight,andhowdotheydifferfromtheprimarycolorswelearninartclass?

Lesson#15:MixingColdLight

Overview:Youcandemonstratehowtheprimarycolorsoflightmixtogetherusingglowsticks.Theglowstickgivesoffitsownlightthroughachemicalreactioncalledchemiluminescence,whichisn’tthesameasmixingpainttogether,sincecupsofpaintarereflectinglight,notgeneratingit.It’slikethedifferencebetweenthesun(whichgivesoffitsownlight)andthemoon(whichyouseeonlywhensunlightbouncesoffittoyoureyeballs).

WhattoLearnThis

Materials

disposabletesttubes red,green,andbluetrue‐colorlightsticks(oneofeach) scissors(withadulthelp) gloves goggles strainer,suchasacoffeefilterorbitofcheesecloth

Experiment

1. Bendthelightstickstobreaktheglassinsidethecontainer(you’llhearalittle“crack”).Dothisforallthreelightsticks.Thiswillactivatethesticks.

2. Slapyourglovesonyourhandsandgogglesonyoureyes.Noexceptions.3. Standoverasinkandcarefullycutoneendoffofthelightsticks.Getanadulttohelp,astheplasticcanbe

stifftocutthrough.4. Carefullypouratinyamountofoneofthecolorsintoyourtesttube.Ifbitsofglasscomeoutalso,usethe

cheeseclothasastrainertocatchthepiecesofglassfrominsidethetube.5. Nowaddasecondcolorandswirlgentlytomix.Recordyourobservationsinthedatatable.6. Repeatsteps4and5foryourdatatable.7. Note:Youmaynotneedallofthered,duetoitslevelofcolorconcentration.Onlyaddabouthalfofthered

andswirluntilthecolorsarecompletelymixed.Addmoreredifneededtoadjustthecolor.8. Whenyouaredonewiththislab,discardthebitsofglassinthetrashandflushtheliquiddownthesink

withplentyofwater.

MixingColdLightDataTable

Color#1 Color#2 Color#3(optional) ResultingColor

Reading

Whenwetalkaboutlight,itsthreeprimarycolorsareactuallyred,green,andblue.Asapainter,youalreadyknowthatmixingthesethreecolorstogetherwouldgetamuddybrown.Butasascientist,whenyoumixtogetherthreecupsofcoldlight,youwillgetsomethingdifferent.You’dgetwhitelight.Thekeyisthatwewouldbemixinglight,notpaint.Mixingthethreeprimarycolorsoflightgiveswhitelight.Ifyoutookthreelightbulbs(red,green,andblue)andshinedthemontheceilingsotheyoverlap,you’dseeawhitespotwherethethreeconverge.Andifyoucouldmagicallyun‐mixthewhitecolors,you’dgettherainbow(whichisexactlywhatprismsdo).Ifyou’rethinkingyellowshouldbeaprimarycolor–itisaprimarycolor,butonlyintheartist’sworld.Yellowpaintisaprimarycolorforpainters,butyellowlightisactuallymadefromredandgreenlight.There’saneasywaytorememberthis:thinkofChristmascolors–redandgreenmergetomaketheyellowstarontopofthetree.Thecoldlightisgivingoffitsownlightthroughachemicalreactioncalledchemiluminescence,whereasthecupsofpaintareonlyreflectingnearbylight.It’slikethedifferencebetweenthesun(whichgivesoffitsownlight)andthemoon(whichyouseeonlywhensunlightbouncesoffittoyoureyeballs).

Note:Ifyou’rewonderingiftherealprimarycolorsforpaintersarecyan,magenta,andyellow,you’reright…butsomefolksstillprefertothinkoftheprimarycolorsasred‐yellow‐blue…eitherway,it’sreallynotimportanttothisexperimentwhichprimarysetyouchoose,sincetheexperimentdealswithlight,notpaint.

Exercises1.Whatcolordoyougetwhenyoumixblueandgreenliquidlights?

2.Whathappenswhenyoustarttoaddtheredlight?

3.Whatisyourfinalcolorresultwhenmixingred,blue,andgreenlights?

4.Howwouldyourresultdifferifyouinsteadmixedred,blueandgreenpaints?

Lesson#16:RefractiveIndexOverview:We’regoingtobendlighttoshowthemagicbehindapopularopticalillusionbyusingacupofliquidasalens.WhattoLearn:Whenabeamoflighthitsadifferentsubstance,itbendsasittravelsthroughthenewsubstance.Thespeedatwhichthelighttravelsandthewavelength(color)alsochanges.Theamountofchangedependsontheindexofrefractionofthematerial.

Materials

paper indexcard pencil scissors ruler disposablecups(4) flashlight rubbingalcohol water babyoil

Experiment

1. Turnoffthelightsandmaketheroomverydark.Ifyoudon’thaveadarkenoughroom,youcandothisexperimentinsideashoebox.

2. Cuttwosmallparallelslitsintheindexcardaboutaninchapart,nothickerthanadime.3. Placeyoursheetofpaperonthetable(seesampleonnextpage).4. Placeanemptycupontopofthepaperandtracearoundthecupsoyouhaveasmallcircleonthepaper.5. Holdtheindexcardupabout4‐6inchesfromthecup.6. Shineyourflashlightthroughtheindexcard,about4moreinchesaway.Youshouldseetwobeamsoflight

hittingthecup.7. Usingyourruler,tracethebeamsoflightfromtheflashlightalongthepaperbeforeandafterthecupand

labelthelines“air.”8. Repeatsteps7‐9byfillingthecupwithadifferentliquideachtimeandtraceeachline.

Cup(ofliquidorgas)

Indexcard

LightfromFlashlight

Reading

Whenabeamoflighthitsadifferentsubstance(likeglass),thelightbendsandthespeedoflightchanges,whichmeansitslowsdownorspeedsupasittravelsthroughthenewsubstance.Thecolorofthelight(calledthewavelength)canalsochange,whichiswhatprismsdotowhitelight:Prismsbendthewhitelightbydifferentamountstogetarainbow.Howmuchthelightbendsdependsontheopticaldensityofthesubstance.Moredensematerialsbendthelightmore.Glassisopticallydenserthanwater,whichisdenserthanair. OpticalDensitiesforSelectMaterials:Vacuum(Space) 1.0000Air 1.0003Ice 1.3100Water 1.3333Pyrex 1.4740Cookingoil 1.4740Diamond 2.4170DidyounoticehowPyrexandcookingoilhavethesameopticaldensity?ThismeansifyouplaceaPyrexcontainerinsideabeakerofvegetableoil,itwilldisappearbecausethelightwillnotbend,soyouwillnotbeabletodetectonefromtheother.ThistrickalsoworksforsomemineraloilsandKarosyrup.(Notehoweverthattheopticaldensitiesofliquidsvarywithtemperatureandconcentration,andmanufacturersarenotperfectlyconsistentwhentheywhipupabatchofthisstuff,sosomeadjustmentsareneeded.)Magnifyinglenses,telescopes,andmicroscopesusethisideaofbendinglighttodistortimagestomakeobjectsappeardifferentsizes.Thelightdoesn’talwaysappeartobend.Forexample,whenlightentersanewsubstance(likegoingfromairtowater)perpendiculartothesurface(lookingstraighton),refractiondoesnotoccur.Whereyouareobservingfromwillaffecthowthelightappearstobend.Exercises

1.Whichsubstancebentthelightthemost?

2.Whatotherkindsofmaterialsdoyouthinkmightworkinthecup?

3.Canweseelightwaves?

Lesson#17:FireandOptics

Becausethisactivityinvolvesfire,makesureyoudothisonaflame‐proofsurfaceandnotyourdiningroomtable!Goodchoicesareyourdriveway,cementparkinglot,theconcretesidewalk,oralargepieceofceramictile.Don’tdothisexperimentinyourhand,oryou’reinforahot,nastysurprise.

Overview:Todayyougettoconcentratelight,specificallytheheat,fromthesunintoaverysmallarea.Normally,thesunlightwouldhavefilleduptheentireareaofthelens,butyou’reshrinkingthisdowntothesizeofthedot.

WhattoLearn:Magnifyinglenses,telescopes,andmicroscopesusethisideatomakeobjectsappeardifferentsizesbybendingthelight.Whenlightpassesthroughadifferentmedium(fromairtoglass,water,alens…)itchangesspeedandusuallytheangleatwhichit’straveling.Aprismsplitsincominglightintoarainbowbecausethelightbendsasitmovesthroughtheprism.Apairofeyeglasseswillbendthelighttomagnifytheimage.

Materials

sunlight glassjar nailthatfitsinthejar 12”thread hairfromyourhead 12”string 12”fishingline 12”yarn paperclip magnifyingglass fireextinguisher adulthelp

ExperimentPleasedothisonafireproofsurface!Thisexperimentwilldamagetables,counters,carpets,andfloors.Dothisexperimentonsurfacelikeconcreteorblacktop.

1. Haveyouradultdothesestepsforyou:a. Holdthemagnifierabovetheleafandbringitdowntowardtheleafuntilyouseeabrightspotform

onitssurface.Adjustituntilyouseethelightasbrightandasconcentratedaspossible.Firstyou’llnoticesmoke,thenatinyflameastheleafburns.

b. Youareconcentratingthelight,specificallytheheat,fromthesunintoaverysmallarea.Normally,thesunlightwouldhavefilleduptheentireareaofthelens,butyou’reshrinkingthisdowntothesizeofthedotthat’sburningtheleaf.

2. Screwthelidonthejar.3. Tieoneendofthethreadtothepaperclip.4. Poketheotherendofthethreadinsidetheholeonthelid.5. Unscrewthelidandtieanailtotheotherendofthethread.Youwantthenailtobehangingabovethe

bottomofthejarbyaninchortwo,soadjusttheheightasneeded.

6. Bringyourjaroutside.7. Question:Withoutbreakingtheglassorremovingthelid,howcanyougetthenailtodroptothebottomof

thejar?

Fire&Optics&EyesDataTable

MaterialforSuspendingNail HowLongDidItTaketoDrop?(measureinseconds)

Reading

Magnifyinglenses,telescopes,andmicroscopesusethisideatomakeobjectsappeardifferentsizesbybendinglight.Whenlightpassesthroughadifferentmedium(fromairtoglass,water,alens…)itchangesspeedandusuallytheangleatwhichit’straveling.Aprismsplitsincominglightintoarainbowbecausethelightbendsasitmovesthroughtheprism.Apairofeyeglasseswillbendthelighttomagnifytheimage.

Thislabisintwoparts.Thedemonstrationyoudowiththekidsisnottheonetheydofortheiractivity.You’regoingtoconcentratethepowerofthesunonaflammablesurface.

Pleasedothisonafireproofsurface!Thisexperimentwilldamagetables,counters,carpets,andfloors.Dothisexperimentonsurfacelikeconcreteorblacktop.

Thermoelectricpowerplantsusethisprincipletopowerentirecitiesbyusingthisprincipleofconcentratingtheheatfromthesun.

Neverlookthroughanythingthathaslensesinitatthesun,includingbinocularsortelescopes,otherwisewhat’shappeningtotheleafrightnowisgoingtohappentoyoureyeball.

Exercises

1. Whathappenedtotheleaf?Why?

2. Howdidyougetthenailtodrop?

3. Whichmaterialignitedthequickest?

Lesson#18:SimpleMicroscopes&Telescopes

Overview:Didyouknowyoucancreateacompoundmicroscopeandarefractortelescopeusingthesamematerials?It'sallinhowyouusethemtobendthelight.Thesetwoexperimentscoverthefundamentalbasicsofhowtwodouble‐convexlensescanbeusedtomakeobjectsappearlargerwhenrightupcloseorfartheraway.

WhattoLearn:Thingslikelensesandmirrorscanbendandbouncelighttomakeinterestingthings,likecompoundmicroscopesandreflectortelescopes.Telescopesmagnifytheappearanceofsomedistantobjectsinthesky,includingthemoonandtheplanets.Thenumberofstarsthatcanbeseenthroughtelescopesisdramaticallygreaterthancanbeseenbytheunaidedeye.

Materials

window dollarbill penny handheldmagnifyinglenses(2) ruler

Experiment

1. Placeapennyonthetable.2. Holdonemagnifierabovethepennyandlookthroughit.3. Bringthesecondmagnifyinglensabovethefirstsonowyou’relookingthroughboth.Movethesecondlens

closerand/orfurtherfromthepennyuntilthepennycomesintosharpfocus.You’vejustmadeacompoundmicroscope.

4. Who’sinsidethebuildingonanolderpenny?5. Tryfindingthespider/owlonthedollarbill.(Hint:it’sinacornernexttothe“1”.)6. Keepingthedistancebetweenthemagnifiersaboutthesame,slowlyliftupthemagnifiersuntilyou’renow

lookingthroughbothtoawindow.7. Adjustthedistanceuntilyourimagecomesintosharp(andupside‐down)focus.You’vejustmadea

refractortelescope,justlikeGalileoused400yearsago.8. Findeightdifferentitemstolookatthroughyourmagnifiers.Makefourofthemup‐closesoyouusethe

magnifiersasamicroscope,andfourofthemfar‐awayobjectssoyouusethemagnifierslikeatelescope.Completethetable.

SimpleMicroscope&TelescopeDataTable

Forthelasttwocolumns,measurewithyourrulercarefully.Don’tforgettolabelyourunits!

MagnificationUsed:______________________________________________(multiplythemagnificationofbothlensestogether)

ObjectLookedAt

DidyouusetheMagnifiersasaMicroscopeor

Telescope?

HowFarApartaretheLenses?

HowFarisyourEyefromtheEyepiece?

Reading

WhatIlikebestaboutthisactivityishoweasilywecanbreakdownthebasicideasofsomethingthatseemsmuchmorecomplexandintimidating,likeatelescopeormicroscopeinawaythatkidsreallyunderstand.

Imaginetossingarockintoastillpondandwatchingthecirclesofripplesformandspreadoutintorings.Nowlookattheripplesinthewater‐noticehowtheyspreadout.Whatmakestheripplesmoveoutwardisenergy.

Theripplesarelikelight.Noticethewavesarenotreallymovingthewaterfromonesideofthepondtotheother,butrathermovingenergyacrossthesurfaceofthewater.

Toputitanotherway,energytravelsacrossthepondinawave.Lightworksthesameway–lighttravelsasenergywaves.Onlylightdoesn'tneedwatertotravelthroughthewaythewaterwavesdo‐itcantravelthroughavacuum(likeouterspace).

Lightcanchangespeedthesamewaysoundvibrationschangespeed.(Thinkofhowyourvoicechangeswhenyouinhaleheliumandthentrytotalk.)

Thefastestlightcangois186,000milespersecond–that'sfastenoughtocircletheEarthseventimeseverysecond,butthat'salsoinsideavacuum.Youcangetlightgoingslowerbyaimingitthroughdifferentgases.Inourownatmosphere,lighttravelsslowerthanitdoesinouterspace.

Exercises

1. Canlightchangespeeds?

2. CanyouseeALLlightwithyoureyes?

3. Givethreeexamplesofalightsource.

4. What'sthedifferencebetweenamicroscopeandatelescope?

5. Whyisthetelescopeimageupside‐down?

Light1Evaluation

StudentWorksheet

Overview:Todayyou’regoingtotaketwodifferenttests:thequizandthelabpractical.You’regoingtotakethewrittenquizfirst,andthelabpracticalattheendofthislab.Thelabpracticalisn’tapapertest–it’siswhereyougettoshowyourteacherthatyouknowhowtodosomething.

LabTest&Homework

1. Yourteacherwillcallyouupsoyoucansharehowmuchyouunderstandaboutthebasicsoflightandhowitworks.Sincescienceissomuchmorethanjustreadingabookorcirclingtherightanswer,thisisanimportantpartofthetesttofindoutwhatyoureallyunderstand.

2. Whileyouarewaitingforyourturntoshowyourteacherhowmuchofthisstuffyoualreadyknow,yougettochoosewhichhomeworkassignmentyouwanttocomplete.Theassignmentisduetomorrow,andhalfthecreditisforcreativityandtheotherhalfisforcontent,soreallyletyourimaginationflyasyouworkthroughit.Chooseone:a. Writeashortstoryorskitaboutlightfromtheperspectiveofthephotonorthewave.You’llreadthis

aloudtoyourclass.b. Makeaposterthatteachesthemainconceptsaboutlightwaves.Whenyou’refinished,you’lluseitto

teachtoaclassintheyoungergradesanddemonstrateeachoftheprinciplesthatyou’velearned.c. Writeandperformapoemorsongaboutlight.Thiswillbeperformedtoyourclass.

Light1Quiz

Name__________________________________________________________1. Whatarethethreeprimarycolorsoflight?

2. Whatcolordoyougetwhenmixingtheprimarycolorsoflight?

3. Whatisalightsource?Pleasegiveanexample.

4. Whatpropertycanhelpmakesomethingagoodprismmaterial?

5. Whatisalightreflector?Pleasegiveanexample.

6. DoesthesunalwayslightuphalftheMoon?

7. HowmanyphasesdoestheMoonhave?

8. Howdoesyoureyeworklikeacamera?

9. Whatisthedifferencebetweenconvexandconcave?

10. CanyouseeALLlightwithyoureyes?

11. Givethreeexamplesofalightsource.

12. What'sthedifferencebetweenamicroscopeandatelescope?

Light1LabPracticalStudentWorksheet

Thisisyourchancetoshowhowmuchyouhavepickeduponimportantkeyconcepts,andifthereareanyholes.Youalsowillbeworkingonahomeworkassignmentasyoudothistestindividuallywithateacher.

Materials:

Twomagnifyinglenses Glassofwater Pencil

LabPractical:

Designandbuildanexperimentthatshowshowtochangethespeedoflight.

Designasimplemicroscopetolookatoneofyourhairsfromyourhead.

AnswerstoExercisesandQuizzes

Lesson #1: Rainbow Shadows 1.Whatarethethreeprimarycolorsoflight?(red,blue,andgreen)2.Whatcolordoyougetwhenmixingtheprimarycolorsoflight?(white)3.Howdoyoumixtheprimarycolorsoflighttogetyellow?(greenandredlightmakeyellowlight)4.Usecrayonsorcoloredpencilstodrawwhatyousawwhenallthreelightswereshiningonthewallandyouwavedyourhandinfrontofthelight.Lesson #2: Kaleidoscopes 1.Whatisalightsource?Pleasegiveanexample.(asourceoflightwaves–thesun,lightbulbs,fire,etc.areallexamples)2.Whatisalightreflector?Pleasegiveanexample.(Areflectordoesnotemitlight.Insteaditbounceslightoffofitandreflectsthelightbacktooureyes.Water,mirrors,themoonareallexamples.)3.Sketchanimageofsomethinginterestingthatyouwereabletoseeasthelightreflectedfromthemultiplesurfacesofthekaleidoscopetoyoureyes.Lesson #3: Liquid Prism 1.Whatservesastheprisminthisexperiment?(waterorotherclearliquid)2.Whatpropertycanhelpmakesomethingagoodprismmaterial?(transparency:amaterialthatallowslighttopassthroughit)3.Whataresomeotheritemsthatcouldbeusedasprisms?(glass,oil,clearplastic)Lesson #4: Lunar Phases 1.DoesthesunalwayslightuphalftheMoon?(Yes.Wedon’talwaysgettoseeit,whichisbecausetheMoonhasphases.)2.HowmanyphasesdoestheMoonhave?(eight)3.WhatisitcalledwhentheMoonappearstogrow?(waxing)4.WhatisitcalledwhenyouseemorelightthandarkontheMoon?(gibbous)5.Howlongdoesittakeforacompletelunarcycle?(about29½days)Lesson #5: Sky in a Jar 1.Whatcolorsdoesthesunsetgothrough?(Thesunsetgoesthroughthecolorsoftherainbowasthesunsetslowerinthesky,startingwithyellow,thenorange,andthenredasitsets.)2.Doesthecolorofthelightsourcematter?(Yes.Whitelightgivesthebestresults.)Lesson #6: Light Tricks 1.Whenonecoinisinthewater,youcanactuallyseetwo:Arethecoinsboththesamesize?Whichoneistheoriginalcoin?(thesmallercoinisthereflection)2.Instep2oftheexperiment:Howmanycoinsaretherewhenviewedfromthetopoftheglass?Whataboutwhenyoulookfromtheside?(onecoinwhenlookingfromabove,twowhenlookingthroughtheside)3.Whathappenedwhenyoutossedinasecondcoin?(Therewerefour.)4.Howdidyouroutlinescompare?(Thefirstwasacircle,thesecondwasanoval.)

Lesson #7: Black Light Treasure Hunt 1.Whyareincandescentlightslessenergy‐efficientthanfluorescentlights?(Incandescentlightgiveoffmoreheatandlesslight–theyloseenergytoheatandfluorescentlightsdonot.)2.Whatarethetwotypesoffluorescentlight?(Phosphorescenceandtriboluminescience)3.Whatkindsofthingsdidyoufindthatglowonyourtreasurehunt?Giveatleastfiveexamples.(answersvary)Lesson #8: Benham’s Disk 1.Whatcolorswereyouabletoseewhenthediskswerespinning?(answersvary)2.Howdidthedifferentpatternslookwhentheywerespun?(answersvary)3.Howdidspeedanddirectionaffectwhatyousaw?(answersvary)Lesson #9: Eye Balloon 1.Howdoesyoureyeworklikeacamera?(Bothhavelenses,bothproduceimageswithlotsofcomponentsworkingtogether.)2.Howcanyoutellifalensisdoubleconvex?(Whenyourunyourfingersacrossit,youfeeltwobumpsoneachside.)3.Whatisthedifferencebetweenconvexandconcave?(Aconcavesurfacecurvesinward,whileaconvexsurfacebulgesout.)4.Canyougiveanexampleofaneverydayobjectthathasbothaconvexandaconcaveside?(spoon)5.Howcanyouchangetheballoontomakeitnear‐sighted?(lightlypushdownonthetop)6.Howcanyouchangetheballoontomakeitfar‐sighted?(gentlypushinfrontandbackoftheballoontomakeittaller)Lesson #10: Disappearing Frog 1.Whatdidyounoticeaboutthevisionofthestudentandtheblindspotthatyoumeasured?(answersvary)2.Whydoyouthinkit’simportanttoknowwhereyourblindspotis?(soyoucanexpectitandworkarounditifyouneedto)Lesson #11: Pinhole Camera 1.Howdotheimagesappearwhenthey’reprojectedontothepaperinsideyourcamera?(upside‐down)2.Whydoyouthinkit’simportanttomaketheboxaslight‐proofaspossible?(itallowsonlyasmallamountoflighttopassthroughsothatwecanseethereflectionbetter)3.Isthereapartofyourbodythatworkssimilarlytothepinhole?(oureyes)4.Sketchapictureofsomethingyousawthroughyourpinholecamera.Lesson #12: Diffraction 1.Whichlightsourcegavethemostinterestingresults?(Thisvarieswithdata.)2.Whathappenswhenyouaimalaserbeamthroughthediffractiongrating?(Itsplitsintothreebeamsoflight,asshowninthesecondvideo.)3.HowisaCDdifferentandthesameasadiffractiongrating?(ACDhasaspiraloffinely‐spaceddatatrackswhilethediffractiongratinghasaseriesofparallellines.TheCDsplitsthelightthesamewayasthediffractiongrating.TheCDsplitsthebeamintomorethanthreebeams.)4.Whydoesthefeatherwork?(Therearetiny“hairs”onthefeatherthatareactingliketinyprisms.)Lesson #14: Mixing Colors 1.Whatdoyouseewhenblueandredaremixedonthespinner?(purple)2.Whatdoyouseeredandgreenaremixedonthespinner?(yellow)

3.Whatcolorswouldyoumixtogetorange?(redandyellow)4.Whataretheprimarycolorsoflight,andhowdotheydifferfromtheprimarycolorswelearninartclass?(Red,blue,andgreenaretheprimarycolorsoflight–inart,theprimarycolorsarered,yellow,andblue.)Lesson #15: Mixing Cold Light 1.Whatcolordoyougetwhenyoumixblueandgreenliquidlights?(answersvary–greentoblue)2.Whathappenswhenyoustarttoaddtheredlight?(thecolorstartstopale)3.Whatisyoufinalcolorresultwhenmixingred,blue,andgreenlights?(white)4.Howwouldyourresultdifferifyouinsteadmixedred,blueandgreenpaints?(itwouldbeabrowncolor)Lesson #16: Refractive Index 1.Whichsubstancebentthelightthemost?(oil)2.Whatotherkindsofmaterialsdoyouthinkmightworkinthecup?(answersvary)3.Canweseelightwaves?(yes)Lesson #17: Fire and Optics 1.Whathappenedtotheleaf?Why?(Youareconcentratingthelight,specificallytheheat,fromthesunintoaverysmallarea.Normally,thesunlightwouldhavefilleduptheentireareaofthelens,butyou’reshrinkingthisdowntothesizeofthedotthat’sburningtheleaf.)2.Howdidyougetthenailtodrop?(Byconcentratingtheenergyfromthesunusingthemagnifier.)3.Whichmaterialignitedthequickest?(Refertodatatable.)Lesson #18: Simple Microscopes & Telescopes 1.Canlightchangespeeds?(Yes,whenittravelsthroughdifferentmediums.)2.CanyouseeALLlightwithyoureyes?(No,onlyvisiblelight,likearainbow.)3.Givethreeexamplesofalightsource.(Answerwillvary,butherearemine:sun,acandle,andaglowstick.)4.What'sthedifferencebetweenamicroscopeandatelescope?(Amicroscopemagnifiesanimagebeforethefocalpoint;atelescopemagnifiesanimageafterthefocalpoint.Bothareusedtomakeimagesappearcloserandlarger.Amicroscopeisusedwhenobjectsarenear;atelescopeisusedforfarawayobjects.)5.Whyisthetelescopeimageupside‐down?(Becauseyou’vefocusedtheimagebeyondthefocalpoint.)

VocabularyfortheUnitThethreeprimarycolorsoflightarered,blue,andgreen.Redandgreenlightmixedtogethermakeyellowlight.Prismsunmixlightintoitscolors(wavelengths).

Concavelensesworktomakeobjectssmaller(doorpeephole),andarecurvedinwardlikeacave.

Convexlensesmakethemlarger(magnifyinglenses),andhavea”bump”inthemiddleyoucanfeelwithyourfingers.

Theamountofenergyaphotonhasdetermineswhetherit’saparticleorawave.Photonswiththelowestamountsofenergyandlongestwavelengths(somearethesizeoffootballfields)areradiowaves.Thenextstepuparemicrowaves,whichhavemoreenergythanradiowaves.IRhasslightlymoreenergy,andvisiblelight(therainbowyoucanseewithyoureyes)hasmoreenergyandshorterwavelengths.Ultraviolet(UV)lighthasmoreenergythanvisible,andX‐rayshaveevenmoreenergythanUV,andfinallythedeadlygammarayshavethemostamountofenergy.

Filterscanbeusedtoblockcertainwavelengths.

Intensity,orbrightness,istheamountofphotons(packetsoflight)youhaveinacertainamountofspace.Aflashlighthaslessintensitythanacarheadlight.

LASERstandsforLightAmplificationbyStimulatedEmissionofRadiation.Mostlasersaremonochromatic(onecolor).Lasersareconcentratedbeamsoflight,andareilluminatedbysmallparticles(likesmokeanddust).

Lensesworktobendlightinacertaindirection(refraction).Alensisacurvedpieceofglassorplasticthatchangesthespeedofthelight.Lenseshavethesameeffectonlasersasonlightbeams.

Lightcanbedefinedbyfourthings:intensity(howbright),frequency(orwavelength),polarization(thedirectionoftheelectricfield),andphase(timeshift).

Objectscaneitherbealightsource(likethesun)orreflectlight(likethemoon).

Lightcanchangespeeds,butthemaximumlightspeedisthroughavacuum(186,000milespersecond).Lightchangesspeedswhenitpassesthroughadifferentmaterial(likewater,glass,orfog).

Dependingontheopticaldensityofthematerial,lightwillbendbydifferentamounts.Glassisopticallydenserthanwater.Waterismoreopticallydensethanair.

Whentwobeamsoflightareoutofphasewitheachother,it’slikeplayingaGandAonthepiano.Thisiscalledphaseshift.

BlueandUVlightejectelectronsfrommetalplates,butredlightdoesnot(photoelectriceffect).

Polarizationhastodowiththedirectionoftheelectricfield.Yoursunglassesarepolarizingfilters,meaningthattheyonlyletlightofacertaindirectionin.

Whenabeamoflighthitsawindow,itbendsandchangesspeed(refraction).Technically,thewavelength(color)changesbutthefrequencystaysthesame.Inorderforthistohappen,thespeedoflightmustalsochange.

Razor‐edgeslitscreateinterferencepatterns.Slitsareskinnyholesthatallowlighttopassthrough.Scientistsuseslitstofilteroutallotherlightsourcesexcepttheonetheywanttouseintheirexperiment.

Whenyouchangethewavelength,youchangethecolorofthelight.Thewavelength()equalsthespeedoflight(c)dividedbythefrequency(),or=c/.

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