M23_KNIG9404_ISM_C23.pdf

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1、23RAYOPTICSConceptualQuestions23.1.Thereisalreadysomuchambientscatteredlightreflectedfromtheroadthatthelittlebitmoreaddedbyyourheadlightsisnotnoticeable.You’veprobablynoticedthisatdusk.Evenafterthesungoesdownbutitisn’treallydarkyetweturnonourlights,butthisismoretobevisiblebyothe

2、rdriversthantohelpusseetheroadbetter.Asitgetsdarkeranddarkeroureyesadjusttothelesseramountoflightandourownheadlightsreflectingfromtheroadaheadmakemoreandmoreofabeneficialdifference.23.2.Theshapeofasmallpinholedoesnotmateriallyaffecttheimageinapinholecamera.Theremightbeminordiffe

3、rencesinqualityoffocus,buttheimageonthefilmwillbegenerallythesamewhetherthepinholeisroundorsquare.23.3.Lightisscatteredoffallpointsofthepencilandintoalldirectionsofspace.Iflightdirectedtowardthemirrorisreflectedintoyoureye,youseetheimageofthepencil.(a)Aspart(a)ofthefigureshows,i

4、fthetophalfofthemirroriscovered,lightscatteredfromthepencilandreflectedoffthemirrorcanenteryoureyeandyouwillseetheimageofthepencil.(b)Aspart(b)ofthefigureshows,ifthebottomhalfofthemirroriscovered,lightscatteredfromthepencilcannotbereflectedoffthemirrorinsuchamannerthatitentersyo

5、ureye.Youcannotseetheimageofthepencil.©Copyright2013PearsonEducation,Inc.Allrightsreserved.Thismaterialisprotectedunderallcopyrightlawsastheycurrentlyexist.Noportionofthismaterialmaybereproduced,inanyformorbyanymeans,withoutpermissioninwritingfromthepublisher.23-123-2Chapter2323

6、.4.Thespeedoflightinamediumisafunctionoftheindexofrefractionofthatmedium(v=c/n).Ifyouuseopticfiberatthecenter(wherethelightwouldhaveashortertraveldistance)withalargerindexofrefraction,youwillslowthelightdownanditwillgettotheendofthefiberclosertothetimetheotherlightgetsthere.23.5

7、.Section1:Blue;allothercolorsareabsorbed.Section2:Black;lightessentiallydoesnotgetthrough.Section3:Red;allothercolorsareabsorbed.23.6.Thecardisredbecauseitreflectsredlightandabsorbstheothercolors.Whenitisilluminatedbyredlighttheredlightreflectsoffthecardintoyoureyesandyouseether

8、edcardasred.Ifthecardisilluminatedwithbluelight