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1、精品文档1996年8月托福阅读全真试题Questions1-10ThewordlaserwascoinedasanacronymforLightAmplificationbytheStimulatedEmissionofRadiation.Ordinarylight,fromtheSunoralightbulb,isemittedspontaneously,whenatomsormoleculesgetridofexcessenergybythemselves,withoutanyoutsideintervention.Stimulatedemission
2、isdifferentbecauseitoccurswhenanatomormoleculeholdingontoexcessenergyhasbeenstimulatedtoemititaslight.AlbertEinsteinwasthefirsttosuggesttheexistenceofstimulatedemissioninapaperpublishedin1917.However,formanyyearsphysiciststhoughtthatatomsandmolecules2016全新精品资料-全新公文范文-全程指导写作–独家原创34
3、/34精品文档alwaysweremuchmorelikelytoemitlightspontaneouslyandthatstimulatedemissionthusalwayswouldbemuchweaker.ItwasnotuntilaftertheSecondWorldWarthatphysicistsbegantryingtomakestimulatedemissiondominate.Theysoughtwaysbywhichoneatomormoleculecouldstimulatemanyothertoemitlight,amplify
4、ingittomuchhigherpowers.ThefirsttosucceedwasCharlesH.Townes,thenatColombiaUniversityinNewYork.Insteadofworkingwithlight,however,heworkedwithmicrowaves,whichhaveamuchlongerwavelength,andbuiltadevicehecalleda“maser”forMicrowaveAmplificationbythe2016全新精品资料-全新公文范文-全程指导写作–独家原创34/34精品文档
5、StimulatedEmissionofRadiation.Althoughhethoughtofthekeyideain1951,thefirstmaserwasnotcompleteduntilacoupleofyearslater.Beforelong,manyotherphysicistswerebuildingmasersandtryingtodiscoverhowtoproducestimulatedemissionatevenshorterwavelength.Thekeyconceptsemergedabout1957.TownesandA
6、rthurSchawlow,thenatBellTelephoneLaboratories,wrotealongpaperoutliningtheconditionsneededtoamplifystimulatedemissionofvisiblelightwaves.Ataboutthesametime,similarideascrystallizedinthemindofGordonGould,thena37-year-oldgraduatestudentatColumbia,whowrotethem2016全新精品资料-全新公文范文-全程指导写作–
7、独家原创34/34精品文档downinaseriesofnotebooks.TownesandSchawlowpublishedtheirideasinascientificjournal,PhysicalReviewLetter,butGouldfiledapatentapplication.Threedecadeslater,peoplestillargueaboutwhodeservesthecreditfortheconceptofthelaser.1.Theword“coined”inline1couldbestbereplacedby(A)cr
8、eated(B)mentioned(C)understood(D)
