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Sensors,Circuits,andSatellitesLesson1:WaveGenerator

Sensors,Circuit,andSatellitesisacollectionofclassroomlessonscreatedbyNASA’sAuramissioneducationandoutreachthatexploretheelectromagneticspectrumandNASAremotesensinginstrumentsusingstudentassembledcircuits.Theselessonsintegrateinquirywithactive-learningexperiencestoengagestudentsinthepropertiesofelectromagneticenergyandremotesensing.TheinvestigationsaresequencedtohelpthelearnerconstructtheirknowledgeabouttheelectromagneticspectrumwhileofferingrealworldexamplesfromNASA.Credits:Dr.DeborahRoberts-Harris,Dept.ofTeacherEducationattheUniversityofNewMexicoGingerButcher,SeniorNASAEducationSpecialist,ScienceSystemsandApplications,Inc.DevelopedincollaborationwithlittleBitsElectonics™viaanInternalResearchandDevelopment(IRADFY13-297)awardfromNASAGoddardSpaceFlightCenterandcontinuedcollaborationunderNASASpaceActAgreementSAA5-2013-3-N15210

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Lesson1:WaveGeneratorSummary:Thislessonusessoundtodemonstratehowenergytravelswaves.Studentswillinvestigatesoundenergycreatedbyvibrationsofaspeakerandvisiblyexperiencetheenergyasvibrationscreatewavesinaliquid.Conceptsofwavelengthandfrequencyareintroduced.StudentObjectives:Studentswillidentifydifferenttypesofenergyandwhentheytransferfromonetoanother.Studentswillexplorehowsoundisenergyandtravelsinwavesandthenexplainhowwavelengthandfrequencyareusedtodescribewaves.

KeyTerms:Potentialenergy,kineticenergy,soundenergy,electricalenergy,compressionwaves,wavelength,frequencyApproximateTime:30-45minutes

Materials:• littleBits™components:power,wire,speaker,brightled

o ALTERNATEMATERIALS–Amplifiedspeakerwithoutgrill/screencoverandwithinputconnecterforMP3playerorotheraudiosource

• plasticspoon,repositionabletape(lowtackmaskingtape)• opaqueliquidsuchasmilk(smallliquidcoffeecreamersworkwell)• MP3playerorcomputerwithabilitytoplaymusic• Accesstointernetduringorbeforedemonstration

NGSS–DisciplinaryCoreIdeas• MS-PS4-1WavesandTheirApplicationsinTechnologiesforInformation

Transfer-Usemathematicalrepresentationstodescribeasimplemodelforwavesthatincludeshowtheamplitudeofawaveisrelatedtotheenergyinawave.[ClarificationStatement:Emphasisisondescribingwaveswithbothqualitativeandquantitativethinking.][AssessmentBoundary:Assessmentdoesnotincludeelectromagneticwavesandislimitedtostandard.**Inadditiontoamplitude,energyofawavecanvarybywavelengthandfrequency.Thediscussioninthislessonrelatesenergyofawavetothefrequency.

• MS-PS4-2WavesandTheirApplicationsinTechnologiesforInformationTransfer-Developanduseamodeltodescribethatwavesarereflected,absorbed,ortransmittedthroughvariousmaterials.[ClarificationStatement:Emphasisisonbothlightandmechanicalwaves.Examplesofmodelscouldincludedrawings,simulations,andwrittendescriptions.][AssessmentBoundary:Assessmentislimitedtoqualitativeapplicationspertainingtolightandmechanicalwaves.]

NGSS–Cross-cuttingconcept• StructureandFunction:Structurescanbedesignedtoserveparticularfunctions

bytakingintoaccountpropertiesofdifferentmaterials,andhowmaterialscanbeshapedandused.

Set-up:

• PuttogetherthecircuitusinglittleBits™components:power+microphone(withaudiocable)+wire+speaker

• AttachMP3playerorcomputerviatheaudiocableandqueueupmusic.(trythisaheadoftimewithyourownmusictofindasongthatcreateseasilyvisiblewaves

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–somegenresthatworkwellarehiphop,funkandpopaslongasthereisagoodbasetrack)

Engage:Thisdemonstrationshouldbedonebytheteacherinacentrallocationsothatthestudentsmightbestandingorsittinginacirclearoundthedemosothatallcansee.Tip-tryitafewtimesyourselfbeforedemonstratinginfrontofstudents.

1. Askstudentsiftheycanidentifyanytypesofenergypresentedinthiscircuit.[Chemicaland/orstoredenergy=Battery.Electricalenergy=thepowerbit&cable.Kineticenergyand/orsoundenergy=thevibrationofthespeaker.]

imagecredit:littleBits™

2. Playasongandaskafewstudentvolunteerstogentlytouchthespeaker.“Whatishappening?”[Introduceorreinforce‘kineticenergy’]Whatishappeningthatourearscanhearthesoundfromthespeaker?

3. Thenconnectaplasticspoontothespeaker.Use‘repositionable’tape(commonlyusedforscrapbooking)toattachtheendofthespoonhandletooneedgeofthespeaker.Thespoonhandleshouldtouchthecentersilverpartofthespeaker,thepartthatvibrates.(Hint:asmallballofclayplacedbetweenthecenterofthespeakerandthespoonhandlewillhelpmakethephysicalconnectionsothevibrationstransferfromthespoonhandletotheliquid.Trythisaheadoftimewiththeliquidtoensurethevibrationsarevisible.)

imagecredit:littleBits™

4. Fillspoonwithasmallamountofopaqueliquidandplaymusic.Askstudentsto

watchwhathappens.AskastudentvolunteertochartstudentAskstudent

Repositionable tape

Plastic spoonSmall ball of clay or dough

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volunteertochartstudents’responsestothequestions:Whatishappening?Whatdoyousee?Whatdoyouhear?

Explore:Playdifferenttypesofmusic-classicalmusicandsongswithalotofbassworkwell.Witheachtypeofmusic,askwhatishappening?Whatdoyousee?Whatdoyouhear?(Againastudentvolunteercanchartresponses,orstudentscaneachrecordtheirobservationsintheirownjournal)Explain:Askstudentstosharetheirideasaboutwhatishappeningbetweenthevibrationsofthespeakerwiththeliquidinthespoon.Thevibrationsfromthespeakervibratethespooncausingwavestoformintheliquid.Theycanactuallyseesoundenergycreatingwavesintheliquid!Thewavesintheliquidarealsoenergyintheformofpressure(orcompression)waves.Likewavesintheocean,itisanexampleofenergytravelingthroughamedium(water)aswaves.Teachernote–thewavesintheliquidarenot‘actual’soundwaves.Weareseeingtheaffectsofthevibrationsfromthespeakerintheliquid.Soundwavesarecompressionwavesintheair(orthroughtheplasticofthespoon)producedbythevibrationofthespeaker.Thelengthsofsoundwavesaremuchlonger(seeextend).Askstudentstosharetheirideasaboutthevibrationsofthespeakerandthesoundwehear.Howareweabletohearthemusicwithourears?Ifweknowthatenergytravelsinwaves,whatishappeningbetweenthespeakerandourears?Doyouthinkthereissoundinouterspace?WhyorWhynot?Thespeakeristransferringtheelectricalenergytosoundenergybycreatingsoundwavesintheair.Astheconeonthespeakervibrates,itpushesontheairmoleculescreatingwaves.Thevibrationsmovethroughtheaircausingthesurroundingmoleculestovibrateinaparticularpatternrepresentedbyawave.Thevibratingairthencausesthelistener'seardrumtovibrateinthesamepattern.Thus,ourearsdetectthisenergy–thesecompressionwaves–assound.Todemonstratethisconceptforvisuallearners,havetwostudentsholdeachendofaslinky.Then,haveoneofthestudentscreateacompressionwavepulsebyquicklytappingthebackoftheirhandthatisholdingtheslinky.Studentscanobservethewave

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movingthroughtheslinky.Soundiscreatedbytheairbeingcompressedbyvibrationsjustliketheslinky,itcreatesawavebycompressingthecoils.Explore:Playatoneatdifferentfrequencies.Tonesbyspecificfrequency–Hertz–canbegeneratedonlineatwebsitessuchashttp://onlinetonegenerator.com)Trythreeormoretonesbetween60and600Hertz.Teachernote–ifyoudonothaveaccesstotheInternetduringthislesson,youcandownloadthetonesfromthewebsiteinadvance.Askstudentstodescribetherelationshipbetweenwhattheyarehearing,thenumberofHertz,andwhattheyareseeingintheliquid.Beforeeachnewtone,askstudentstopredicthowthisnewtonewillsounddifferentandlookdifferentintheliquid.Teachernote–higherfrequencieshaveshorterwavelengths,havehigherpitchandhavesmallerwavesorripplesintheliquid.Thelowerthefrequency,thewavelengthislongerandthepitchlower.Sincethewavelengthsarelonger,thereisalargerimpactonthedishandpossiblysplashout.Extend:Wavescanbedescribedbytheirwavelength(distancefromcresttocrest)orbytheirfrequency(numberofwavesthatpassthroughapointinasecond).Hertzisatermusedtomeasurethefrequencyasonecycle(fromcresttothenextcrest)persecond.Ifweknowthespeedofsoundis343meterspersecond(mps),thenwecandivideitbythefrequencytodeterminethelengthofthewave.

speedofsoundfrequency = wavelength

Shareexplanationaboutfrequency.Alowfrequencymeansfewerwaves(justonefor1Hertz)cancyclepastagivenpointinonesecond.Ahigherfrequency-suchas600Hertz–alargernumberofwavescancycleinonesecond.Formorewavestocycleinsecond,theywouldhavetohavesmallerwavelengths.Soalowfrequencyhasalongerwavelengththanahigherfrequency.

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Evaluate:Usingtheworksheet,UnderstandingWaveLENGTH,Studentswillputthefourexamplesinthefollowingworksheet,UnderstandingWaveLENGTH,inorderofwavelength–fromlongesttoshortestandprovideevidencefortheiranswers(Answer:C,D,A,B-evidenceprovidedbytheassociatedconversionequationnotedinrednexttoeachanswer).

• A.MiddleConapianois261Hz(343mps/261Hz=1.31m)• B.Shortestwavelengthofsoundabatcanhearis3millimeters(3mm=0.003m)• C.LowestfrequencyanElephantcanhearis5hertz(343mps/5Hz=68.6m)• D.Shortestwavelengthofsoundahumancanhearis17meters(17m)

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Name:______________________________________________________________UnderstandingWaveLENGTHWavescanbedescribedbytheirwavelength(distancefromcresttocrest)orbytheirfrequency(numberofwavesthatpassthroughapointinasecond).Hertzisatermusedtomeasurethefrequencyasonecycle(fromcresttothenextcrest)persecond.Ifweknowthespeedofsoundis343meterspersecond(mps),thenwecandivideitbythefrequencytodeterminethelengthofthewave.

𝒔𝒑𝒆𝒆𝒅𝒐𝒇𝒔𝒐𝒖𝒏𝒅𝒇𝒓𝒆𝒒𝒖𝒆𝒏𝒄𝒚 = 𝒘𝒂𝒗𝒆𝒍𝒆𝒏𝒈𝒕𝒉

Putthefollowingfourexamplesinorderofwavelength–fromlongesttoshortestandprovideevidenceforyouranswers.Hint:Usetheequationaboveandtheinformationfromtheparagraphtoconvertfrequencytowavelengthifnecessary.

A. MiddleConapianois261Hz

B. Shortestwavelengthofsoundabatcanhearis3millimeters

C. LowestfrequencyanElephantcanhearis5hertz

D.Shortestwavelengthofsoundahumancanhearis17meters__________________,__________________,__________________,_______________Shortest Longest