Conceptual Physical Science Explorations

Chapter 13: Light and Color

Why the Sky Is Blue

The molecules of the atmosphere vibrate at blue frequencies when zapped by the Sun, which is whey they appear blue. The sky, containing all these blue shining molecules, thus also appears blue. Duration: 4:15.

VIDEO QUIZ

Table of Videos

Chapter 1: About Science
- 1.1 A Brief History of Advances in Science
- 1.2 Mathematics and Conceptual Physical Science
- 1.3 Scientific Methods—Classic Tools
- 1.4 Scientific Hypotheses Must Be Testable
- 1.5 A Scientific Attitude Underlies Good Science
- 1.6 The Search for Order—Science, Art, and Religion
- 1.7 Technology—Practical Use of the Findings of Science
- 1.8 The Physical Sciences: Physics, Chemistry, Earth Science, and Astronomy
- 1.9 In Perspective
Chapter 2: Newton's First Law of Motion
- 2.1 Aristotle’s Classification of Motion
- 2.2 Galileo’s Concept of Inertia
- 2.3 Galileo’s Concepts of Speed and Velocity
- 2.4 Motion is Relative
- 2.5 Newton’s First Law of Motion—The Law of Inertia
- 2.6 Net Force—The Combination of All Forces That Act on an Object
- 2.7 Equilibrium for Objects at Rest
- 2.8 The Support Force—Why We Don’t Fall Through the Floor
- 2.9 Equilibrium for Moving Objects
- 2.10 Earth Moves Around the Sun
Chapter 3: Newton's Second Law
- 3.1 Galileo Developed the Concept of Acceleration
- 3.2 Force Causes Acceleration
- 3.3 Mass Is a Measure of Inertia
- 3.4 Mass Resists Acceleration
- 3.5 Newton’s Second Law Links Force, Acceleration, and Mass
- 3.6 Friction Is a Force That Affects Motion
- 3.7 Objects in Free Fall Have Equal Acceleration
- 3.8 Newton’s Second Law Explains Why Objects in Free Fall Have Equal Acceleration
- 3.9 Acceleration of Fall Is Less When Air Drag Acts
Chapter 4: Newton's Third Law
- 4.1 A Force Is Part of an Interaction
- 4.2 Newton’s Third Law—Action and Reaction
- 4.3 A Simple Rule Helps Identify Action and Reaction
- 4.4 Action and Reaction on Objects of Different Masses
- 4.5 Action and Reaction Forces Act on Different Objects
- 4.6 The Classic Horse-Cart Problem—A Mind Stumper
- 4.7 Action Equals Reaction
- 4.8 Summary of Newton’s Three Laws
Chapter 5: Momentum
- 5.1 Momentum is Inertia in Motion
- 5.2 Impulse Changes Momentum
- 5.3 Momentum Change is Greater When Bouncing Occurs
- 5.4 When No External Force Acts, Momentum Doesn’t Change—It is Conserved
- 5.5 Momentum is Conserved in Collisions
Chapter 6: Energy
- 6.1 Work—Force x Distance
- 6.2 Power—How Quickly Work Gets Done
- 6.3 Mechanical Energy
- 6.4 Potential Energy Is Stored Energy
- 6.5 Kinetic Energy Is Energy of Motion
- 6.6 Work-Energy Theorem
- 6.7 Conservation of Energy
- 6.8 Machines—Devices to Multiply Forces
- 6.9 Efficiency—A Measure of Work Done for Energy Spent
- 6.10.Sources of Energy
- 6.11 Energy for Life
Chapter 7: Gravity
- 7.1 The Legend of the Falling Apple
- 7.2 The Fact of the Falling Moon
- 7.3 Newton’s Grandest Discovery—The Law of Universal Gravitation
- 7.4 Gravity and Distance: The Inverse-Square Law
- 7.5 The Universal Gravitational Constant, G
- 7.6 The Mass of the Earth Is Measured
- 7.7 Projectile Motion
- 7.8 Fast-Moving Projectiles—Satellites
- 7.9 Earth Satellites in Circular Orbits
- 7.10 Satellites in Elliptical Orbits
- 7.11 Escape Speed—Getting “Out There”
- 7.12 Gravitation Is Universal
Chapter 8: Fluid Mechanics
- 8.1 Density—A Measure of Compactness
- 8.2 Pressure—Force per Area
- 8.3 Buoyancy in a Liquid
- 8.4 Archimedes’ Principle—Sink or Swim
- 8.5 Pressure in a Gas
- 8.6 Atmospheric Pressure Is Due to the Weight of the Atmosphere
- 8.7 Pascal’s Principle—The Transmission of Pressure in a Fluid
- 8.8 Buoyancy in a Gas—More Archimedes’ Principle
- 8.9 Bernoulli’s Principle—Flying With Physics
Chapter 9: Heat
- 9.1 Thermal Energy—The Total Energy in a Substance
- 9.2 Temperature—Average Kinetic Energy Per Molecule in a Substance
- 9.3 Absolute Zero—Nature’s Lowest Possible Temperature
- 9.4 Heat Is the Movement of Thermal Energy
- 9.5 Specific Heat Capacity— A Measure of Thermal Inertia
- 9.6 Thermal Expansion
- 9.7 Conduction—Heat Transfer via Particle Collision
- 9.8 Convection—Heat Transfer via Movements of Fluid
- 9.9 Radiation—Heat Transfer via Radiant Energy
- 9.10 Energy Changes With Changes of Phase
Chapter 10: Electricity
- 10.1 Electric Charge Is a Basic Characteristic of Matter
- 10.2 Coulomb’s Law—The Force Between Charged Particles
- 10.3 Charge Polarization
- 10.4 Electric Current—The Flow of Electric Charge
- 10.5 An Electric Current Is Produced by Electrical Pressure—Voltage
- 10.6 Electrical Resistance
- 10.7 Ohm’s Law—The Relationship Among Current, Voltage, and Resistance
- 10.8 Electric Shock
- 10.9 Direct Current and Alternating Current
- 10.10 Electric Power—The Rate of Doing Work
- 10.11 Electric Circuits—Series and Parallel
Chapter 11: Magnetism
- 11.1 Magnetic Poles—Attraction and Repulsion
- 11.2 Magnetic Fields—Regions of Magnetic Influence
- 11.3 Magnetic Domains—Clusters of Aligned Atoms
- 11.4 The Interaction Between Electric Currents and Magnetic Fields
- 11.5 Magnetic Forces Are Exerted on Moving Charges
- 11.6 Electromagnetic Induction—How Voltage Is Created
- 11.7 Generators and Alternating Current
- 11.8 Power Production—A Technological Extension of Electromagnetic Induction
- 11.9 The Induction of Fields—Both Electric and Magnetic
Chapter 12: Waves and Sound
- 12.1 Special Wiggles—Vibrations and Waves
- 12.2 Wave Motion—Transporting Energy
- 12.3 Two Types of Waves—Transverse and Longitudinal
- 12.4 Sound Travels in Longitudinal Waves
- 12.5 Sound Can Be Reflected
- 12.6 Sound Can Be Refracted
- 12.7 Forced Vibrations and Natural Frequency
- 12.8 Resonance and Sympathetic Vibrations
- 12.9 Interference—The Addition and Subtraction of Waves
- 12.10 The Doppler Effect—Changes in Frequency Due to Motion
- 12.11 Wave Barriers and Bow Waves
- 12.12 Shock Waves and the Sonic Boom
Chapter 13: Light and Color
- 13.1 The Electromagnetic Spectrum
- 13.2 Why Materials Are Either Transparent or Opaque
- 13.3 Reflection of Light
- 13.4 Refraction—The Bending of Light Due to Changing Speed
- 13.5 Illusions and Mirages Are Caused by Atmospheric Refraction
- 13.6 Color Science
- 13.7 Mixing Colored Lights
- 13.8 Mixing Colored Pigments
- 13.9 Why the Sky Is Blue
- 13.10 Why Sunsets Are Red
- 13.11 Why Clouds Are White
Chapter 14: Properties of Light
- 14.1 Light Dispersion and Rainbows
- 14.2 Lenses
- 14.3 Image Formation by a Lens
- 14.4 Diffraction—The Spreading of Light
- 14.5 Interference—Constructive and Destructive
- 14.6 Interference Colors by Reflection from Thin Films
- 14.7 Polarization—Evidence for the Transverse Wave Nature of Light
- 14.8 Wave-Particle Duality—Two Sides of the Same Coin
Chapter 15: The Atom
- 15.1 Discovering the Invisible Atom
- 15.2 Elements and the Periodic Table
- 15.3 The Atomic Nucleus Consists of Protons and Neutrons
- 15.4 Isotopes and Atomic Mass
- 15.5 Electron Shells—Regions About the Nucleus Where Electrons Are Located
Chapter 16: Nuclear Physics
- 16.1 Radioactivity—The Disintegration of the Atomic Nucleus
- 16.2 Alpha, Beta, and Gamma Rays
- 16.3 Environmental Radiation
- 16.4 Transmutation of Elements—Changing Identities
- 16.5 Half-Life Is a Measure of Radioactive Decay Rate
- 16.6 Isotopic Dating Measures the Ages of Materials
- 16.7 Nuclear Fission’The breaking Apart of Atomoic Nuclei
- 16.8 The Mass-Energy Relationship: E = mc2
- 16.9 Nuclear Fusion—The Combining of Atomic Nuclei
Chapter 17: Elements of Chemistry
- 17.1 Chemistry is Known as the Central Science
- 17.2 The Submicroscopic World is Super-Small
- 17.3 The Phase of Matter Can Change
- 17.4 Matter Has Physical and Chemical Properties
- 17.5 Determining Physical and Chemical Changes Can Be Difficult
- 17.6 The Periodic Table Helps Us to Understand the Elements
- 17.7 Elements Can Combine to From Compounds
- 17.8 There Is a System for Naming Compounds
Chapter 18: Bonds and Molecular Attractions
- 18.1 Electron-Dot Structures Help Us to Understand Bonding
- 18.2 Atoms Can Lose or Gain Atoms to Become Ions
- 18.3 Ionic Bonds Result from a Transfer of Electrons
- 18.4 Metal Atoms Bond by Losing Their Electrons
- 18.5 Covalent Bonds Result from a Sharing of Electrons
- 18.6 Electrons May Be Shared Unevenly in a Covalent Bond
- 18.7 Electrons Are Shared Unevenly in a Polar Molecule
- 18.8 Molecules Are Attractive
Chapter 19: How Chemicals Mix
- 19.1 Most Materials Are Mixtures
- 19.2 The Chemist’s Classification of Matter
- 19.3 A Solution Is a Single-Phase Homogenous Mixture
- 19.4 Concentration Is Given as Moles per Liter
- 19.5 Solubility Measures How Well a Solute Dissolves
- 19.6 Soap Works by Being Both Polar and Nonpolar
- 19.7 Purifying the Water We Drink
Chapter 20: How Chemicals React
- 20.1 Chemical Reactions Are Represented by Chemical Equations
- 20.2 Reaction Rates Can Be Slow or Fast
- 20.3 Catalysts Speed Up Chemical Reactions
- 20.4 Chemical Reactions Can Be Either Exothermic or Endothermic
- 20.5 Chemical Reactions Are Driven By Entropy
Chapter 21: Acids/Bases and Redox
- 21.1 Acids Donate and Bases Accept
- 21.2 Some Acids and Bases Are Stronger than Others
- 21.3 Solutions Can Be Acidic, Basic, or Neutrals
- 21.4 Rainwater Is Acidic and Ocean Water Is Basic
- 21.5 Oxidation Is the Loss of Electrons and Reduction Is the Gain of Electrons
- 21.6 The Energy of Flowing Electrons Can Be Harnessed
- 21.7 Oxygen Is Responsible for Corrosion and Combustion
- 21.8 Hydrogen Sulfide Can Induce Suspended Animation
Chapter 22: Organic Compounds
- 22.1 Hydrocarbons
- 22.2 Unsaturated Hydrocarbons
- 22.3 Functional Groups
- 22.4 Alcohols and Ethers
- 22.5 Amines and Alkaloids
- 22.6 Carbonyl Compounds
- 22.7 Polymers
Chapter 23: The Nutrients of Life
- 23.1 Biomolecules Are Molecules Produced and Used by Organisms
- 23.2 Carbohydrates Give Structure and Energy
- 23.3 Lipids Are Insoluble in Water
- 23.4 Proteins Are Polymerns of Amino Acids
- 23.5 Nucleic Acids Code for Proteins
- 23.6 Vitamins Are Organic, Minerals Are Inorganic
- 23.7 Metabolism Is the Cylcing of Biomolecules Through the Body
- 23.8 The Food Pyramid Summarizes a Healthful Diet
Chapter 24: Medicinal Chemistry
- 24.1 Medicines Are Drugs That Benefit the Body
- 24.2 The Lock-and-Key Model Guides Chemists in Creating New Medicines
- 24.3 Chemotherapy Cures the Host by Killing the Disease
- 24.4 The Nervous System Is a Network of Neurons
- 24.5 Psychoactive Drugs Alter the Mind or Behavior
- 24.6 Pain Relievers Inhibit the Transmission or Perception of Pain
Chapter 25: Rocks and Minerals
- 25.1 Our Rocky Planet
- 25.10 The Rock Cycle
- 25.2 What is a Mineral?
- 25.3 Mineral Properties
- 25.4 Classification of Rock-Forming Minerals
- 25.5 The Formation of Minerals and Rock
- 25.6 Rocks Are Divided Into Three Main Groups
- 25.7 Igneous Rocks Form When Magma Cools
- 25.8 Sedimentary Rocks Blanket Most of Earth’s Surface
- 25.9 Metamorphic Rocks Are Changed Rocks
Chapter 26: The Architecture of Earth
- 26.1 Earthquakes Make Seismic Waves
- 26.2 Seismic Waves Reveal Earth’s Internal Layers
- 26.3 Internal Motion Deforms Earth’s Surface
Chapter 27: Plate Tectonics
- 27.1 Continental Drift—An Idea Before its Time
- 27.2 Search For the Mechanism to Support Continental Drift
- 27.3 The Theory of Plate Tectonics
- 27.4 Three Types of Plate Boundaries
- 27.5 The Theory That Explains Much
Chapter 28: Shaping Earth's Surface
- 28.1 The Hydrologic Cycle
- 28.2 Groundwater—Water Below the Surface
- 28.3 The Work of Groundwater
- 28.4 Streams and Rivers—Water at Earth’s Surface
- 28.5 The Work of Surface Water
- 28.6 Glaciers and Glaciation—Earth’s Frozen Water
- 28.7 The Work of Glaciers
- 28.8 The Work of Air
Chapter 29: A Brief History of Earth
- 29.1 Relative Dating—The Placement of Rocks in Order
- 29.2 Radiometric Dating Reveals the Actual Time of Rock Formation
- 29.3 Geologic Time
- 29.4 Precambrian Time—A Time of Hidden Life
- 29.5 Paleozoic Era—A Time of Life Diversification
- 29.6 The Mesozoic Era—The Age of Reptiles
- 29.7 The Cenozoic Era—The Age of Mammals
- 29.8 Earth History in a Capsule
Chapter 30: The Oceans and Atmosphere
- 30.1 Earth’s Atmosphere and Oceans
- 30.2 Components of Earth’s Atmosphere
- 30.3 Solar Energy
- 30.4 Driving Forces of Air Motion
- 30.5 Global Atmospheric Circulation Patterns
- 30.6 Components of Earth’s Oceans
- 30.7 Oceanic Circulation
Chapter 31: Weather
- 31.1 Water in the Atmosphere
- 31.2 Weather Variables
- 31.3 There Are Many Different Clouds
- 31.4 Air Masses, Fronts, and Storms
- 31.5 Weather Can Be Violent
- 31.6 The Weather—Number One Topic of Conversatio
Chapter 32: The Solar System
- 32.1 The Solar System Is Mostly Empty Space
- 32.2 Solar Systems Form from Nebula
- 32.3 The Sun Is Our Prime Source of Energy
- 32.4 The Inner Planets Are Rocky
- 32.5 The Outer Planets Are Gaseous
- 32.6 Earth’s Moon
- 32.7 Failed Planet Formation
Chapter 33: Stars
- 33.1 Observing the Night Sky
- 33.2 Stars have Different Brightness and Color
- 33.3 The Hertzburg-Russell Diagram Describes Stars
- 33.4 The Life Cylce of Stars
- 33.5 Novae and Supernovae Are Stellar Explosions
- 33.6 Supergiant Stars Collapse into Black Holes
Chapter 34: Galaxies and the Cosmos
- 34.1 A Galaxy Is an Island of Stars
- 34.2 Elliptical, Spiral, and Irregular Galaxies
- 34.3 Active Galaxies Emit Huge Amounts of Energy
- 34.4 Galaxies Form Clusters and Superclusters
- 34.5 Galaxies Are Moving Away from One Another
- 34.6 Further Evidence for the Big Bang
- 34.7 Dark Matter is Invisible
- 34.8 Dark Energy Opposes Gravity