Waves & Electromagnetic Radiation Chapter 6 Great Idea: Whenever an electrically charged object is accelerated, it produces electromagnetic radiation—waves of energy that travel at the speed of light
Chapter Outline The Nature of Waves The Electromagnetic Wave The Electromagnetic Spectrum
The Nature of Waves
Energy Transfer by Waves Wave –A traveling disturbance Properties of Waves –Wavelength –Frequency –Velocity –Amplitude
The Relationship Among Wavelength, Frequency, and Velocity Velocity of a wave –Equation:
The Two Kinds of Waves: Transverse and Longitudinal Transverse –Motion is perpendicular to wave direction Longitudinal –Motion is same direction as wave
Interference –Constructive Interference Act together –Destructive Interference Cancellation
The Electromagnetic Wave
The Anatomy of the Electromagnetic Wave Point A –Maximum strength, but decreasing Point B –Minimum strength, but increasing Electromagnetic waves continue through internal mechanisms and transfer energy as they travel
Light & The Energy of Electromagnetic Waves Speed of Light –All electromagnetic waves have same velocity –c=300,000km/s Energy –Higher frequency=blue color –Lower frequency=red color
The Doppler Effect Doppler Effect –Wave motion is independent of its source –If source moves, frequency appears to change
Transmission, Absorption, and Scattering Transmission –Wave passes through matter Absorption –Wave & energy are absorbed Scattering –Waves absorbed and reemitted Diffuse scattering Reflection
The Electromagnetic Spectrum
Maxwell’s equations –Predicted more waves Hertz –Radio waves
Radio Waves & Microwaves Radio Waves –Range: kilohertz to hundreds of megahertz –Longest waves Microwaves –Range: 1mm-1m
Infrared Radiation –Range: 1mm-1µ All warm objects emit radiation
Visible Light –Range: 700nm-400nm Colors –Slices of electromagnetic spectrum
Ultraviolet Radiation –Range: 400nm-100nm –Shorter wavelength=more energy Damage to cells Fluorescence
X-rays & Gamma Rays X-rays –Range: 100nm-0.1nm –High-frequency –Medicine Gamma Rays –Range: 0.1nm ( m) m –Highest frequency –Medicine –Astronomy