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Chapter 15. Waves. Section 1. Types of Waves. Waves. A wave is a disturbance that carries energy through matter or space. Types of Waves. Mechanical Electromagnetic. Mechanical waves. a wave that requires a medium through which to travel Medium: the matter through which a wave travels.
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Chapter 15 Waves
Section 1 Types of Waves
Waves • A wave is a disturbance that carries energy through matter or space
Types of Waves • Mechanical • Electromagnetic
Mechanical waves • a wave that requires a medium through which to travel • Medium: the matter through which a wave travels
Electromagnetic Waves • a wave that consists of electric and magnetic fields • Does not need a medium • This is how light from the sun reaches earth through empty space (there is no matter in space)
Transverse Wave • a wave that moves perpendicularly to the particle motion. • Example: “the wave” at a sporting event http://go.hrw.com/resources/go_sc/interactOnline/hk/hkwav_io.swf
Longitudinal Waves • A wave that moves parallel to the particle motion. • Example: sound waves https://www.youtube.com/watch?v=aguCWnbRETU
Wave Parts • Crest: top of the wave • Trough: bottom of the wave • Rarefaction: stretched out areas • Compression: crowded areas
Section 2 Characteristics of Waves
Properties of Waves • Amplitude: height of the wave • Higher the amplitude the more energy the wave carries
Wavelength (λ): distance between the crests of two waves • Shorter the wavelength the more energy the wave carries
Period (T): the time that it takes a wave to pass • SI Unit: seconds (s) • Frequency (f): the number of waves produced in a given amount of time • SI Unit: Hertz (Hz) • Higher the frequency the more energy the wave carries
Wave Speed • How fast a wave moves (m/s) wave speed = frequency × wavelength v = f × λ
The Electromagnetic Spectrum • Shows the energy, frequency and wavelength of all the types of electromagnetic waves
Visible Light • We can see electromagnetic waves with wavelengths between 400nm and 700nm • Humans see these waves as the color of the rainbow (ROYGBIV)
Sound Waves • The pitch of a sound (how high or low it is) depends on the frequency at which sound waves hit your eardrum • high-pitch = high frequency
The Doppler Effect • Motion between the source of waves and the observer creates a change in pitch.
Section 3 Wave Interactions
What are Wave Interactions? • When waves hit a boundary the wave bounces back. • When two or more waves are in the same location. • When a wave passes the edge of an object or passes through an opening, the wave bends. • A wave also bends when it passes from one medium to another.
Reflection • When a ray of light, sound, or heat bounces back after it hits a surface
Diffraction • When a wave bends because the wave finds an obstacle or an edge
Refraction • The bending of a wave as it passes from one medium to another. • Example: when light passes from air to water
Interference • When two or more waves collide and combine to form one wave