ReferenceforTeaching一、异域风情1
AlexanderBell'sGreatInventionMostpeopleknowthatAlexanderGrahamBellinventedthetelephone
Butnotmanyknowaboutaccothertalkingdeviceheinventedjustfouryearslater,in1880
Hecalledthedevicethephotophone
‘Photophone’comesfromtheGreekwordsfor‘light’and‘sound’
Thephotophonedidnotuseelectricitytocarrysoundoverwiresbetweentwopeople
That'swhatatelephonedoes
Instead,thephotophoneusedabeamofsunlighttravellingthroughtheair
Withhisinvention,Bellcouldactuallytransmithumanspeechonabeamoflight
Todoso,hespokeclosetoathinmirrorthatwasreflectingsunlight
Thevibrationsofhisvoicecausedthemirrortovibrate,andthevibratingmirrorcausedthelighttovibrate
Thevibratinglighthitalight-sensitivecellinareceiverplacedsomedistanceaway
Thecellchangedthelightpatternsintoelectricalsignals
Earphone