waves & electromagnetic radiation chapter 6 great idea: whenever an electrically charged object...
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The Nature of WavesTRANSCRIPT
Waves & Electromagnetic Radiation
Chapter 6Great 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: fv λ=
The Two Kinds of Waves: Transverse and Longitudinal
• Transverse– Motion is perpendicular to wave
direction• Longitudinal
– Motion is same direction as wave
Interference
• 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
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
• Infrared Radiation– Range: 1mm-1µ
• All warm objects emit radiation
Visible Light
• Visible Light– Range: 700nm-400nm
• Colors– Slices of electromagnetic spectrum
Ultraviolet Radiation
• 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 (10-10m)-10-12m– Highest frequency– Medicine– Astronomy