Physics in the Arts WHAT IS THE COMPLEMENTARY SCIENCE SERIES? Wehopeyouenjoythisbook.Ifyouwouldliketoreadotherqualityscience books with a similar orientation see the order form and reproductions of the frontandbackcoversofotherbooksintheseriesattheendofthisbook. TheComplementaryScienceSeriesisanintroductory,interdisciplinary,and relativelyinexpensiveseriesofpaperbacksforscienceenthusiasts.Theseries covers core subjects in chemistry, physics, and biological sciences but often from an interdisciplinary perspective. They are deliberately unburdened by excessivepedagogy,whichisdistractingtomanyreaders,andavoidtheoften ploddingtreatmentinmanytextbooks. These titles cover topics that are particularly appropriate for self-study although they are often used as complementary texts to supplement stan- dard discussion in textbooks. Many are available as examination copies to professorsteachingappropriatecourses. Theserieswasconceivedtofillthegapsintheliteraturebetweenconventional textbooks and monographs by providing real science at an accessible level, withminimalprerequisitessothatstudentsatallstagescanhaveexpertinsight intoimportantandfoundationalaspectsofcurrentscientificthinking. Manyofthesetitleshavestronginterdisciplinaryappealandallhaveaplace onthebookshelvesofliteratelaypersons. Physics in the Arts P.U.P.A. Gilbert University of Wisconsin-Madison and W. Haeberli University of Wisconsin-Madison AMSTERDAM•BOSTON•HEIDELBERG•LONDON NEWYORK•OXFORD•PARIS•SANDIEGO SANFRANCISCO•SYDNEY•TOKYO ACADEMIC PRESS AcademicPressisanimprintofElsevier Thecoverimage,byPupaGilbert,capturesallthemainthemesofthisbook:light,color,color generatingmechanisms,photography,music,soundandwaves.Whitelightilluminating thesurfaceofacompactdiscisseparatedintothecolorsofthespectrum,andphotographed. MusicisrepresentedbytheCDitself,acommonmusicmedium,andasoundwave.This oscillationiscomputer-generated,andsimilartoasoundwavedetectedbyamicrophoneand displayedonthescreenofanoscilloscope. DevelopmentEditor:AnitaKoch AcquisitionEditor:JeanneLawson ProjectManager:ChristieJozwiak MarketingManager,US:LeahAckerson MarketingManager,UK:TimMoore CoverDesigner:DennisSchaefer ElsevierAcademicPress 30CorporateDrive,Suite400,Burlington,MA01803,USA 525BStreet,Suite1900,SanDiego,California92101-4495,USA 84Theobald’sRoad,LondonWC1X8RR,UK Thisbookisprintedonacid-freepaper. (cid:3)∞ Copyright(cid:3)c 2008,ElsevierInc.Allrightsreserved. Nopartofthispublicationmaybereproducedortransmittedinanyformorbyanymeans, electronicormechanical,includingphotocopy,recording,oranyinformationstorageand retrievalsystem,withoutpermissioninwritingfromthepublisher. 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Gilbert and Willy Haeberli University of Wisconsin-Madison Contents Introduction xi LightandSound.................................................. xi 1 Light and Light Waves 01 1.1 SpeedofLight.......................................... 05 1.2 ElectromagneticSpectrum............................... 06 1.3 Polarization............................................ 07 2 Reflection and Refraction 10 2.1 SpecularReflectionofLight............................. 10 2.2 RefractionofLight...................................... 14 2.3 TotalInternalReflection................................. 17 2.4 ReflectionandRefractioninDiamonds ................... 21 2.5 TheRainbow........................................... 25 2.6 Questions.............................................. 27 v vi Contents 3 Lenses 30 3.1 ThePrism.............................................. 30 3.2 ConvergingandDivergingLenses........................ 31 3.3 FocalLength........................................... 33 3.4 Images—RealandVirtual............................... 36 3.5 ThreeEasyRays........................................ 39 3.6 TheLensFormula...................................... 41 3.6.1 NoteonMagnification ............................ 45 3.7 LensAberrations....................................... 47 3.7.1 ChromaticAberrations............................ 48 3.7.2 SphericalAberration.............................. 49 3.8 Questions.............................................. 52 4 The Eye 56 4.1 Accommodation........................................ 58 4.2 Eyeglasses............................................. 60 4.3 NearsightedEye........................................ 61 4.4 FarsightedEye ......................................... 62 4.5 AstigmaticEye......................................... 62 5 Photography 63 5.1 TheCamera............................................ 63 5.2 FocusingtheCamera.................................... 64 5.3 ChoosingtheExposureTime............................. 67 5.4 ChoosingtheAperture.................................. 68 5.5 DepthofField.......................................... 69 5.5.1 WhythefNumber?............................... 70 5.6 TheFilm............................................... 71 5.7 DigitalPhotography..................................... 75 5.8 PuttingitAllTogether:TakingaPhotograph............... 76 5.9 Questions.............................................. 80 6 Color and Color Vision 82 6.1 Color.................................................. 82 6.2 ColorSensitivityoftheEye.............................. 84 6.3 PhysicalandPsychologicalColor ........................ 89 Contents vii 6.4 Color:Hue,Saturation,andBrightness.................... 90 6.5 LightInteractionwithotherObjects ...................... 92 6.6 ScatteringorDiffuseReflection.......................... 92 6.7 Questions.............................................. 98 7 Additive Color Mixing 99 7.1 PrimaryColors......................................... 99 7.2 AddingPrimaryColors.................................. 100 7.3 TheColorTriangle...................................... 103 7.4 Low-IntensityColors.................................... 107 7.5 SpectralColors......................................... 107 7.6 Non-SpectralColors.................................... 112 7.7 Summary.............................................. 113 7.8 AdditiveColorMixinginPainting........................ 114 7.9 Questions.............................................. 117 8 Subtractive Color Mixing 118 8.1 Filters................................................. 118 8.2 SubtractivePrimaryColors.............................. 120 8.2.1 Subtractiveprimaries.............................. 122 8.3 ColorPhotography...................................... 124 8.4 Pigments............................................... 125 8.5 ChangeinSaturation.................................... 128 8.6 WhyDoBlueandYellowMakeGreen?................... 130 8.7 ChangeinHue ......................................... 131 8.8 Questions.............................................. 134 9 Color-Generating Mechanisms 136 9.1 IlluminatingLight...................................... 136 9.2 Pigments............................................... 136 9.3 StructuralColor:Iridescence............................. 137 9.4 MoreColor-GeneratingMechanismsDuetoIridescence.... 139 9.5 ColorinGemstones..................................... 142 9.6 MineralColorDuetoChargeTransfer.................... 144 9.7 MineralColorDuetoColorCenters...................... 144 9.8 ColorinGemsDuetoBandGapAbsorptionofLight....... 145 viii Contents 10 Periodic Oscillations 148 10.1 DisplacementGraph:PositionxChangeswithTimet ...... 151 10.2 ThePeriodTandtheFrequencyf ........................ 153 10.3 LargeandSmallNumbers............................... 154 10.4 SpeedofMotion........................................ 154 10.5 Questions.............................................. 156 11 Simple Harmonic Motion 158 11.1 TheSpringConstant.................................... 160 11.2 OscillationFrequencyforSimpleHarmonicMotion(SHM). 161 11.3 WaveShapeofSimpleHarmonicMotion.................. 163 11.4 PhaseAngle............................................ 165 11.5 Questions.............................................. 166 12 Damped Oscillations and Resonance 168 12.1 DampedOscillations—TheConceptof“DampingTime”... 168 12.2 Resonance............................................. 170 12.3 Build-upDecayofMusicalTones........................ 175 12.4 ApplicationsinMusic................................... 175 12.4.1 ResonatorsinMusicalInstruments .................. 175 12.5 Questions.............................................. 177 13 Adding Sound Sources: Beats and Harmony 179 13.1 PrincipleofSuperposition............................... 179 13.2 ThreeSpecialCases..................................... 180 13.2.1 TwoPureTonesoftheSameFrequency.............. 180 13.3 Beats.................................................. 182 13.4 Harmony............................................... 184 13.5 FortheFunofIt:LissajousFigures....................... 185 13.6 Questions.............................................. 188 14 Sound Waves 190 14.1 PropagationofaPulse................................... 190 14.2 LongitudinalandTransverseWaves....................... 192 14.3 SoundWavesinAirAreLongitudinalWaves.............. 193 14.4 SpeedofSoundinAir................................... 195 Contents ix 14.5 WavelengthandFrequency .............................. 196 14.5.1 RelevancetoSizeofInstrumentsorLoudspeakers...... 197 14.6 SoundPropagation...................................... 198 14.7 InterferenceofSoundWaves............................. 199 14.8 ConcertHallAcoustics.................................. 201 14.9 Questions.............................................. 205 15 Sound Perception: Pitch, Loudness, and Timbre 206 15.1 LoudnessandAmplitude................................ 207 15.2 LoudnessandFrequency ................................ 210 15.3 PitchDiscrimination.................................... 213 16 The Ear 214 16.1 ThePartsoftheEar..................................... 214 16.2 PlaceTheoryofPitchPerception......................... 216 16.3 WhatDotheAuditoryNervesTelltheBrain?.............. 217 17 Vibration of Strings 220 17.1 SingleModes........................................... 220 17.2 HigherModes.......................................... 222 17.3 TravelingVersusStandingWaves......................... 223 17.4 TheVoicingFormula.................................... 225 17.5 HowDoModesRelatetoMusic?......................... 226 17.6 DampingofHigherPartials.............................. 227 17.7 PluckedStrings:MissingPartials......................... 227 17.8 PlayingHarmonics...................................... 228 17.9 RealStringsHaveSomeStiffness ........................ 228 17.10 Questions.............................................. 229 18 Pipes 231 18.1 PressurePulseinaPipe................................. 231 18.2 ReflectionsinOpenandClosedPipes..................... 232 18.2.1 BoundaryConditions ............................. 233 18.3 StandingWavesinOpenPipes........................... 233 18.4 FundamentalFrequencyofOpenPipe..................... 234 18.5 HigherModesofOpenPipe ............................. 235 18.6 FundamentalModeofClosedPipe ....................... 237