electromagnetic spectrum tattnall county schools 电磁频谱塔特纳尔县学校课件

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1、TheElectromagneticSpectrumS8P4aElectromagneticwavescomeinmanywavelengthsandfrequencies.Eachoneisusefulindifferentways.ElectromagneticWaveshttp://science.hq.nasa.gov/kids/imagers/ems/index.htmlElectromagneticSpectrumTheelectromagneticspectrumistherangeofall

2、EMfrequenciesTheEMspectrumisasmooth,gradualprogressionfromthelowestfrequenciestothehighest(andwavelengths)RadioWavesWavesthathavethelongestwavelength,thelowestfrequency,andlowestenergyTraveleasilythroughtheatmosphereandmaterialsRadiowavesarebroadcastedbyat

3、ransmitterwhereareceiverpicksupthesignalsandconvertsittosoundwavesRadiostationsusedifferentfrequenciessotheydon’tgetcrossedRadioWavesTwowaystomodulateradiowaveisbychangingtheamplitudeandvaryingthefrequencyAmplitudeisusedforAMFrequencyisusedforFMTelevisions

4、alsouseradiowaves…theyuseAMsignalsforthepictureandFMforthesoundMicrowavesHaveshorterwavelengths,higherfrequencies,andhigherenergythanotherradiowavesImportantusesofmicrowavesareradarsandcellphonesRadars(WWII)transmitsmicrowaves,receivesreflections,andconver

5、tsitintovisualimagesRadarledtotheinventionofthemicrowaveovenMicrowavesYourcellphoneisactuallyaradiotransmitterandreceiverthatusesmicrowavesSendsandreceivessignalsfromatowerandiswherethesignalscometogetherandallowyoutoconnectwithotherpersonInfraredLightFoun

6、dbetweenmicrowavesandvisiblelight,isthetypeofEMwavesmostoftenassociatedwithheatYoucannotseeinfraredlight,butyoucanfeeltheresultsExamples:WarminglightsatrestaurantsandyourtoasterVisibleLightPartoftheEMspectrumthathumanscanseeandisthesmallestpartofthespectru

7、mThelongestwavelengthis“red”andtheshortestis“violet”Thevisiblelightfromthesuniswhitelight(allwavelengthsarecombined)VisibleLightTherangeofcolorsiscalledthevisiblespectrumVisibleLightusedinmanywaysVisionFindfoodandothersurvivalactivitiesPlantsneedittomaketh

8、eirfoodCanyouthinkofanythingelse?Wheredoesitcomefrom?MostofitcomesfromthesunTheproductionoflightbymaterialsathightemperaturesiscalledincandescenceOthersourcesinclude:LighteningandFireLivingthingsproducelightL