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