Light and Waves: A Conceptual Exploration of Physics

Description

This book explores light and other types of waves, using this as a window into other aspects of physics. It emphasizes a conceptual understanding, using examples chosen from everyday life and the natural environment. For example, it explains how hummingbird feathers create shimmering colors, how musical instruments produce sound, and how atoms stick together to form molecules. It provides a unique perspective on physics by emphasizing commonalities among different types of waves, including string waves, water waves, sound waves, light waves, the matter waves of quantum mechanics, and the gravitational waves of general relativity. This book is targeted toward college non-science majors, advanced high school students, and adults who are curious about our physical world. It assumes familiarity with algebra but no further mathematics and is classroom-ready with many worked examples, exercises, exploratory puzzles, and appendices to support students from a variety of backgrounds. Preface Contents 1 Theories of Light 1.1 Ancient Ideas About Light 1.1.1 Extramission Theory 1.1.2 Particle Theory 1.2 Islamic Golden Age 1.3 The Particle-Wave Debate 1.3.1 Wave Theory 1.4 Particle-Wave Duality 1.4.1 Today 1.5 Looking Ahead 1.6 Summary 1.7 Exercises Exercises Part IWaves 2 Properties of Waves 2.1 Introduction to Waves 2.1.1 What Is a Wave? 2.1.2 Amplitude and Wavelength 2.2 Characterizing Waves 2.2.1 Types of Waves 2.2.2 Transverse and Longitudinal Waves 2.2.3 Waves in 1, 2, and 3 Dimensions 2.3 Speed and Velocity 2.3.1 Speed and Velocity Equations 2.3.2 Speed of Light 2.3.3 Measuring the Speed of Light* 2.3.4 Speed of Light in a Medium 2.3.5 High Frequency Stock Market Trading and the Speed of Light* 2.4 Frequency and Period 2.4.1 Cars on a Road Analogy 2.4.2 Relating Velocity, Frequency, and Wavelength 2.4.3 Frequency 2.4.4 Frequency and Wavelength in a New Medium 2.5 Summary 2.6 Exercises 3 Superposition 3.1 Superposition of Waves 3.1.1 The Superposition Principle 3.1.2 Superposition with Different Frequencies 3.1.3 Constructive and Destructive Interference 3.1.4 Oscillations in Time 3.1.5 Constructive and Destructive Interference Examples* 3.1.6 Beating Patterns 3.2 Standing Waves 3.2.1 Reflection at Boundaries 3.2.2 Standing Waves from Reflected Waves and Superposition 3.2.3 Standing Waves Between Two Boundaries 3.3 Interference 3.3.1 Thin-Film Interference 3.3.2 Examples of Thin-Film Interference* 3.3.3 Interferometers and the Lack of an Aether* 3.4 Diffraction 3.4.1 Diffraction Through Holes and Around Obstacles 3.4.2 Huygens's Principle 3.5 Combining Diffraction and Interference 3.5.1 Double-Slit Experiment 3.5.2 Double-Slit Experiment Analysis* 3.5.3 Diffraction Gratings* 3.5.4 Single-Slit Experiment and Analysis* 3.5.5 The Arago-Poisson Spot* 3.5.6 Babinet's Principle 3.6 Structural Coloration* 3.7 Summary 3.8 Exercises Exercises 4 Wave Energy 4.1 Energy and Power 4.1.1 Energy 4.1.2 Energy Units 4.1.3 Wave Energy 4.1.4 Power 4.1.5 Energy Density and Power Density 4.2 Spectra 4.2.1 Intensity Spectra 4.2.2 Continuous and Line Spectra 4.2.3 Transmission Spectra 4.2.4 Absorption Spectra* 4.3 Resonance 4.3.1 Resonance and Coupling 4.3.2 Two Resonance Examples with String Waves* 4.3.3 Resonance with Electromagnetic Waves 4.3.4 Resonance with Microwaves and Infrared Light* 4.3.5 The Tacoma Narrows and Millennium Bridges* 4.3.6 Resonance is Reversible 4.4 Non-Resonant Energy Transfer 4.4.1 Abrupt Energy Transfer to Waves 4.4.2 Energy Loss From Damping 4.5 Summary 4.6 Exercises 5 Doppler Effects, Redshifts, and Blueshifts 5.1 Doppler Effect Concepts 5.1.1 The Doppler Effect for Sound Waves 5.1.2 Cars on a Road Analogy 5.1.3 Doppler Effect Applications* 5.1.4 Red and Blue Shifts 5.1.5 Gravitational and Cosmological Redshifts* 5.2 Doppler Effect Equations 5.2.1 Moving Observer Case 5.2.2 Moving Source Equation 5.2.3 General Equation 5.2.4 Doppler Shifts for Reflections 5.2.5 Doppler Effect on Wave Power* 5.2.6 Relativistic Doppler Effect* 5.3 Supersonic Motion 5.3.1 Explanation 5.3.2 Equations for Supersonic Motion* 5.4 Summary 5.5 Exercises 6 Mechanical Waves 6.1 Pendulums 6.1.1 How Pendulums Work 6.1.2 Momentum 6.2 String Waves 6.2.1 How String Waves Work 6.2.2 Speed of String Waves 6.3 Sound Waves 6.3.1 How Sound Waves Work 6.3.2 The Speed of Sound 6.3.3 The Sound Spectrum* 6.3.4 Sonar and Medical Ultrasound* 6.4 The Physics of Music* 6.4.1 Physics Terminology for Music* 6.4.2 The Western Musical Scale* 6.4.3 Musical Intervals* 6.4.4 Major, Minor, and Non-Western Musical Scales* 6.4.5 Musical Instruments* 6.5 Water Waves 6.5.1 Capillary Waves 6.5.2 Gravity Waves 6.5.3 Phase Velocity and Group Velocity 6.5.4 Water Motion in Waves 6.5.5 Water Wave Evolution* 6.5.6 Long Wavelength Water Waves: Tsunamis, Tides, and Seiches* 6.6 Seismic Waves* 6.6.1 The Earth's Structure* 6.6.2 Earthquakes* 6.6.3 Seismic Waves* 6.7 Summary 6.8 Exercises Part IIRays 7 Shadows and Pinhole Cameras 7.1 Shadows 7.1.1 Projection 7.1.2 Analyzing Projections* 7.1.3 Umbra and Penumbra 7.2 Eclipses 7.2.1 Solar Eclipses 7.2.2 Lunar Eclipses 7.2.3 Eclipses and Moon Phases 7.3 Light Through Small Holes 7.3.1 Pinhole Cameras and Camera Obscuras 7.3.2 Pinhole Camera Analysis 7.3.3 Multiple Pinholes* 7.4 Shadow-Based Vision* 7.5 Summary 7.6 Exercises 8 Reflection 8.1 Reflection in General 8.1.1 Why Waves Reflect 8.1.2 Requirements for Mirrors 8.2 Plane Mirrors 8.2.1 Law of Reflection 8.2.2 Corner-Cube Retroreflectors 8.2.3 Images for Plane Mirrors 8.2.4 Size of a Mirror 8.3 Concave Reflectors 8.3.1 Parabolic Reflectors 8.3.2 Concave Spherical Mirrors 8.3.3 Concave Mirror Ray Diagrams 8.3.4 Mirror Equations 8.3.5 Spherical Aberration and Coma* 8.4 Convex Spherical Mirrors 8.5 Multiple Mirrors* 8.6 Mirrors, Inversion, and Symmetry* 8.7 Fermat's Principle of Least Time* 8.8 Summary 8.9 Exercises Exercises 9 Refraction 9.1 Refraction in General 9.1.1 Refractive Index 9.1.2 Why Waves Refract 9.1.3 Refraction From Density Gradients 9.2 Refraction at Interfaces 9.2.1 Snell's Law 9.2.2 Apparent Depth 9.2.3 Refraction and Reflection at Different Angles 9.2.4 Total Internal Reflection Examples* 9.2.5 How Much Light Gets Reflected* 9.2.6 Evanescent Waves* 9.3 Lenses 9.3.1 Types of Lenses 9.3.2 Lens Coordinates 9.3.3 Images From Lenses 9.3.4 Lens Equations 9.3.5 Cameras* 9.3.6 Vision Correction* 9.4 Multiple Lens Systems* 9.4.1 Objects and Images* 9.4.2 Microscopes* 9.4.3 Telescopes* 9.4.4 More Optical Systems* 9.4.5 Electron Microscopes* 9.5 Dispersion 9.5.1 Prisms 9.5.2 Achromatic Lenses* 9.5.3 Rainbows* 9.6 Fermat's Principle of Least Time* 9.7 Summary 9.8 Exercises Part IIILight 10 Color 10.1 Color Vision 10.1.1 How Vision Works 10.1.2 Light and Dark Adaptation 10.1.3 Different People see Different Colors* 10.1.4 Color Vision in Animals* 10.2 Color Models 10.2.1 Color Wheel 10.2.2 Light Addition with the RGB Color Model 10.2.3 Light Subtraction with the CMYK Color Model 10.2.4 Leaf Colors in Summer and Fall* 10.2.5 HSV Color Model 10.2.6 Color Spaces* 10.3 Summary 10.4 Exercises 11 Electromagnetic Waves 11.1 Light Waves as Electric and Magnetic Fields 11.1.1 Scalars, Vectors, and Fields 11.1.2 Electric Fields 11.1.3 Magnetic Fields 11.1.4 Changing Electric and Magnetic Fields 11.1.5 Electromagnetic Waves 11.1.6 How Electromagnetic Waves Work* 11.2 The Electromagnetic Spectrum 11.3 Scattering 11.3.1 Scattering Off Large Objects 11.3.2 Scattering Off Medium Size Objects 11.3.3 Scattering Off Small Objects 11.4 Polarization 11.4.1 Electromagnetic Wave Polarization 11.4.2 Polarizers 11.4.3 Multiple Polarizers 11.4.4 Liquid Crystal Displays 11.4.5 Sources of Polarized Light 11.4.6 Polarization as Superposition* 11.4.7 Birefringence and Optical Activity* 11.5 Summary 11.6 Exercises 12 Thermal Radiation 12.1 Thermal Radiation 12.1.1 Qualitative Trends 12.1.2 Blackbodies 12.1.3 Wien's Displacement Law 12.1.4 Color Temperature 12.1.5 Stefan-Boltzmann Law 12.1.6 Remote Temperature Measurement* 12.2 Thermal Radiation Interactions 12.2.1 Radiation Coupling and Emissivity 12.2.2 Two-Way Thermal Radiation 12.3 Earth's Climate* 12.3.1 Earth's Energy Budget* 12.3.2 Greenhouse Effects on Mars and Venus* 12.3.3 Global Warming* 12.4 Summary 12.5 Exercises Part IVModern Physics 13 Photons 13.1 The Quantum Revolution 13.1.1 Explaining Blackbody Radiation 13.1.2 Particles and Waves 13.1.3 What is a Photon? 13.2 Photon Energy 13.2.1 Planck-Einstein Relation 13.2.2 Photoelectric Effect 13.2.3 Photoelectric Effect Examples* 13.2.4 Photochemistry* 13.2.5 Compton Scattering 13.3 Photon Momentum 13.3.1 Classical Momentum 13.3.2 Photon Momentum 13.3.3 Radiometers* 13.3.4 Solar Sails* 13.3.5 Laser Tweezers* 13.3.6 Doppler Cooling* 13.4 Particle-Wave Duality 13.4.1 Quantum Interpretation of the Double-Slit Experiment 13.4.2 Photon Size* 13.4.3 Spectral Broadening of Pulses 13.4.4 Energy-Time Uncertainty 13.4.5 Particle-Wave Duality for Other Wave Types* 13.5 Summary 13.6 Exercises 14 Matter Waves 14.1 Matter Waves 14.1.1 De Broglie Relations 14.1.2 Wave Functions 14.1.3 What is Waving? 14.2 Traveling Matter Waves 14.2.1 Free Particles 14.2.2 Classical and Quantum Roller Coasters 14.2.3 Barriers and Tunneling 14.2.4 Tunneling Examples* 14.3 Diffraction and Interference 14.3.1 Electron Diffraction 14.3.2 Diffraction for Research* 14.3.3 Interference to Test Quantum Mechanics* 14.4 Standing Matter Waves 14.4.1 Electrons in a Cavity 14.4.2 Filling in Electrons 14.4.3 Molecular Vibrations 14.4.4 Structures of Atoms 14.4.5 Chemical Bonds* 14.5 Energy Level Transitions 14.5.1 Light Absorption 14.5.2 Light Emission 14.5.3 Fluorescence 14.5.4 Phosphorescence* 14.5.5 Lasers 14.6 Quantum Weirdness 14.6.1 Heisenberg Uncertainty Principle 14.6.2 Schrödinger's Cat Experiment* 14.6.3 The EPR Paradox* 14.6.4 Quantum Decoherence* 14.6.5 Macroscopic Quantum Systems* 14.7 Summary 14.8 Exercises 15 Gravitational Waves 15.1 Gravity 15.1.1 Newtonian Gravity 15.1.2 Tides 15.1.3 Gravitational Fields 15.2 Gravitational Waves 15.2.1 First Direct Detection 15.2.2 What are Gravitational Waves? 15.2.3 Frequency 15.2.4 Polarization 15.2.5 Energy 15.2.6 Momentum 15.3 Propagating Gravity 15.3.1 Speed of Gravity 15.3.2 Gravitational Near and Far Field* 15.4 Warped Space 15.4.1 The Equivalence Principle 15.4.2 Gravitational Attraction of Light 15.4.3 Curved Space 15.4.4 Ripples in Spacetime 15.5 Gravitational Wave Detection 15.5.1 Existing Observatories 15.5.2 Future Observatories 15.6 Summary 15.7 Exercises A Numbers A.1 Scientific Notation A.1.1 Scientific Notation on a Calculator A.2 More Calculator Advice A.3 Precision A.3.1 Determining Precision in Calculations A.3.2 Propagating Uncertainties A.4 Exercises B Units B.1 Units Are Your Friends B.2 The Metric System B.3 Unit Math B.4 Unit Conversion B.5 Exercises C Algebra C.1 Solving Problems C.2 Expressions and Equations C.2.1 Manipulating Expressions C.2.2 Manipulating Equations C.3 Exponents C.4 Exercises D Geometry D.1 Triangles D.1.1 Similar Triangles D.1.2 Right Triangles and Trigonometry D.2 Perimeters, Areas, and Volumes D.3 Exercises E Additional Resources F Answers to Odd-Numbered Problems G Figure Credits H Useful Facts and Figures Index