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Explore the nature, properties, and interactions of waves in this comprehensive guide. Learn about different types of waves, their energy transfer through mediums or without a medium, and their reflection, refraction, and interference. Discover the relationship between frequency and wavelength, as well as calculations to determine wave speed and period.
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Ch 1 The Energy of Waves 1.1 The Nature of Waves
The Nature of Waves • Wave- Any disturbance that transmits energy through matter or empty space. • Wave Energy • Energy can be carried away from its source by a wave • The material through which the wave travels does not move with the energy.
Energy Transfer Through a Medium • Medium- a substance through which a wave can travel. • Can be a solid, liquid, or gas. • Plural of medium is media • When a particle vibrates (moves back and forth) it can pass its energy to a particle next to it.
Sound waves need a medium • No medium – no sound travels • Mechanical Waves- Waves that need a medium
Waves • https://www.youtube.com/watch?v=al7sFP4C2TY
Energy Transfer Without a Medium • Visible Light • Microwaves • X rays • These are all called electromagnetic waves • Can travel through a medium or through empty space
Electromagnetic spectrum • https://www.youtube.com/watch?v=m4t7gTmBK3g • https://www.youtube.com/watch?v=cfXzwh3KadE
Types of Waves • Transverse Waves- Waves in which the particles vibrate in an up-and-down motion. • Particles move across, or perpendicular to the direction the wave is going. • Crest- The highest point of a transverse wave. • Trough- The lowest point of a transverse wave (between 2 crests)
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Types of Waves • Longitudinal Waves- The particles of the medium vibrate back and forth along the path the wave moves. • Compression- A part of a longitudinal wave where the particles are crowded together. • Rarefaction-A part where the particles are spread apart. • Sound waves are longitudinal waves.
Types of Waves • Surface Wave- A combination of a transverse and longitudinal wave. • A wave that forms at or near the boundary between 2 media • Ocean waves are surface waves.
1.2 Properties of Waves • Amplitude – Height of a wave. • Maximum distance that the particles of a medium vibrate from their rest position. • Rest position is the point where the particles of a medium stay where there are no disturbances. • The larger the amplitude is, the taller the wave is. • The larger the amplitude is, the more energy the wave has
Properties of Waves • Wavelength- The distance between any two crests or compressions next to each other in a wave. • The shorter the wavelength the more energy the wave has.
Properties of Waves • Frequency- The number of waves produced in a given amount of time. • Expressed in Hertz (Hz) • 1 Hz = 1/s • Higher frequency means higher energy
Properties of Waves • Wave Speed: • The speed at which the wave travels • V = λ x f • SI Units
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Frequency and Wavelength Relationship • Frequency and wavelength are inversely related. • An increase in frequency causes a decrease in wavelength • An increase in wavelength causes a decrease in frequency
Calculations • Determine the wave speed of a wave that has a wavelength of 5 m and a frequency of 4 Hz.
Calculations • What is the frequency of a wave if the wave has a speed of 12 m/s and a wavelength of 3 m?
Calculations • A wave has a frequency of 5 Hz and a speed of 18 m/s. What is the wavelength?
Wave Properties • The period of a wave is the time for a particle on a medium to make one complete cycle. • SI Unit = Seconds (s) • Frequency and period are related Frequency refers to how often something happens. Period refers to the time it takes something to happen • Equation: • p = 1/f
Calculations • What is the period of a wave that has a frequency of 4 Hz?
Calculations • A surface wave has a period of 0.5 s and a wavelength of 0.75 m. What is the speed of the wave?
1.3 Wave Interactions • Reflection- A wave bounces back after hitting a barrier. • All waves can be reflected
Wave Interactions • Transmitted Waves • Refraction- The bending of a wave as the wave passes from one medium to another at an angle • Wave speed changes when a wave moves from one medium • Water refraction
Refraction of Different Colors • Dispersion- Light rays are spread out into separate colors. • Each color of light has it’s own wavelength. • Diffraction- The bending of waves around a barrier or through an opening
Reflection/Refraction/Diffraction • https://www.youtube.com/watch?v=UR2rjO0TkU0
Wave Interactions • Interference- Waves occupy the same space at the same time. • Constructive Interference- the crest of one wave overlaps the crest of another wave. • The new amplitude of the combined wave is larger than the original waves • Destructive Interference- The crest of one wave overlaps with the trough of another wave. • The new amplitude of the combined wave is smaller than the original waves. • Interference
Standing Waves • A pattern of vibration that simulates a wave that is standing still. • Certain points are always at the rest position because of total destructive interference of the waves – called nodes. • The crests and troughs of standing waves are called antinodes.
Resonance • When an object vibrating at or near a second object causes that second object to vibrate also. • Breaking glass with resonance