资源描述：
《UNIT 22》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。
1、TEXTONEAlthoughitsymbolisesabrightidea,thetraditionalincandescentlightbulbisadud.Itwasteshugeamountsofelectricity,radiating95%oftheenergyitconsumesasheatratherthanlight.Itslifeisalsorelativelyshort,culminatinginadullpopasitsfilamentfractures.Nowateamofresearche
2、rshasdevisedalightbulbthatisnotonlymuchmoreenergy-efficient—itisalsoexpectedtolastlongerthanthedevicesintowhichitisinserted.Moreover,thelampcouldbeusedforrear-projectiontelevisionsaswellasgeneralillumination.Thetricktoalongerlife,forlightbulbsatleast,istoensure
3、thatthelamphasnoelectrodes.Althoughelectrodesareundeniablyconvenientforpluggingbulbsdirectlyintothelightingsystem,theyarealsothemainreasonwhylampsfail.Theelectrodeswearout.Theycanreactchemicallywiththegasinsidethelightbulb,makingitgrowdimmer.Theyarealsodifficul
4、ttosealintothestructureofthebulb,makingtheruptureofthesesealsanotherpotentialsourceoffailure.ScientistsworkingforCeravision,acompanybasedinMiltonKeynes,inBritain,havedesignedanewformoflampthateliminatestheneedforelectrodes.Theirdeviceusesmicrowavestotransformel
5、ectricityintolight.Itconsistsofarelativelysmalllumpofaluminiumoxideintowhichaholehasbeenbored.Whenthealuminiumoxideisbombardedwithmicrowavesgeneratedfromthesamesortofdevicethatpowersamicrowaveoven,aconcentratedelectricfieldiscreatedinsidethevoid.Ifacylindricalc
6、apsulecontainingasuitablegasisinsertedintothehole,theatomsofthegasbecomeionised.Aselectronsaccelerateintheelectricfield,theygainenergythattheypassontotheatomsandmoleculesofthegasastheycollidewiththem,creatingaglowingplasma.Theresultinglightisbright,andtheproces
7、sisenergy-efficient.Indeed,whereastraditionallightbulbsemitjust5%oftheirenergyaslight,andfluorescenttubesabout15%,theCeravisionlamphasanefficiencygreaterthan50%.Becausethelamphasnofilament,thescientistswhodevelopeditthinkitwilllastforthousandsofhoursofuse—inoth
8、erwords,fordecades.Moreover,thelightitgeneratescomesfromwhatisalmostasinglepoint,whichmeansthatthebulbscanbeusedinprojectorsandtelevisions.Becauseofthis,thelightismuchmoredi
