M24_KNIG9404_ISM_C24

《M24_KNIG9404_ISM_C24》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。

1、24OPTICALINSTRUMENTSConceptualQuestions24.1.Thepicturewillbeunderexposediftheshutterspeedremainsthesame.TheproblemstatedthatDisnotD2changed.I∝.IffisincreasedthenIisdecreasedsothepictureisunderexposed.f224.2.TheanswerisC.Raysfromallpartsoftheobjecthitallpartsofthelens,sothew

2、holeimagestillappears,butbecausetheareaoftheapertureissmallerthentheimagewillbelessbright.Contrarytochoicea,theimageactuallygetssharperbecausetheoff-axisrayscontributetoblurrinessandasmallerapertureeliminatesmanyofthoserays.24.3.Ifyoutrytoseeunderwaterwithnofacemaskthereisl

3、ittlerefractionatthewater-corneaboundarybecausetheindicesofrefractionaresosimilar.Tomakeupforthislossofrefraction(ascomparedtoseeinginair)itwouldbehelpfultohaveglasseswithconverginglenses.24.4.Theformulafortheresolutionofamicroscopedoesnotcontainthemagnification.Itdependson

4、thediameteroftheobjectivelens(bywayofNAandα)butyourfriend’seyepiecehasthesamediameterasyours.Sohisclaimisnotvalid.2.44λf24.5.Equation24.12givesthewidthofthespotaswmin≈.TheminimumspotwidthisachievedforDincomingparallelrayswhenthelens-to-screendistanceisf.(a)Decreasingλdecrea

5、sesw.(b)DecreasingDincreasesw.(c)Decreasingfdecreasesw.(d)Decreasingthelens-to-screendistancemeansthescreenisnolongerinthefocalplaneandthespotislargerthanitsminimuminthefocalplane.2.44λf24.6.Youwouldusealenswithasmallf-number.Theminimumwidthisgivenbywmin≈butsinceDf-number=f

6、D/,thenwfmin≈2.44(-number).λ1.22λ24.7.Equation24.13givestheangularresolutionofatelescopeasθmin=.TwoobjectsaremarginallyDresolvableifαθ=min(ouroriginalcondition)andareresolvableifαθ>min.(a)Yes,usingashorterwavelengthdecreasesθminwhichmakesαθ>min,sotheresolutionisimproved.(b)

7、Changingthefocallengthdoesnotaffecttheresolutionbecausefisnotintheformulaforresolution.(c)Yes,usingalargerlensincreasestheresolution;increasingDdecreasesθminwhichmakesαθ>min.(d)Changingmagnificationdoesnotaffecttheresolution.©Copyright2013PearsonEducation,Inc.Allrightsreser

8、ved.Thismaterialisprotectedunderallcopyrightlawsastheycurrentlyexist.Noportionofth