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Waves

Waves. Wave Energy. Wave -any disturbance that transfers energ y from one place to another without transferring matter transfer energy AWAY from the source of the energy Medium – material through which wave energy is transferred

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Waves

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  1. Waves

  2. Wave Energy • Wave-any disturbance that transfers energy from one place to another without transferring matter • transfer energy AWAY from the source of the energy • Medium – material through which wave energy is transferred • waves travel fastest through solids because molecules are closer together

  3. Mechanical Waves • Mechanical Waves – a wave that can travel only through matter. (They need a medium-(solid, liquids, or gasses) • Types of Mechanical Waves: • Sound Waves- (longitudinal waves) • Water Waves- (orbital waves) • Seismic Waves-( longitudinal and transverse)

  4. Mechanical Waves - Transverse • Transverse Waves: • the disturbance is perpendicular to the direction the wave travels • move in an up-and-down motion • top of the wave is called the crest and the base of the wave is called the trough

  5. Mechanical Waves - Longitudinal • Longitudinal Waves • the disturbance moves parallel to the direction the wave travels • move in a back-and-forth motion • where particles are crowded together is called the compression, where they are farther apart is called the rarefaction

  6. Mechanical Waves – Orbital • Orbital Waves-(Surface waves) • combination of a transverse wave and a longitudinal wave • ocean waves are an example of surface waves • the water moves up and down while the wave energy moves forward • objects in an ocean wave bob up and down in a circular motion

  7. WRITING RESPONSE What do waves transfer from place to place? What kind of materials can mechanical waves move through?

  8. Electromagnetic (EM) Waves • Electromagnetic Waves (EM) – can travel through empty space and through matter; does NOT need a medium • All electromagnetic waves are transverse • ex. light waves, x-rays, ultraviolet waves, microwaves, radio waves • The type of EM waves given off by an object depends mainly on the temperature of the object • Ex: humans give off infrared rays

  9. PROPERTIES OF WAVES

  10. Amplitude– the height of a wave, from resting position to crest • the larger the amplitude, the more energy the wave has • Wavelength – distance from any point on a wave to an identical point on the next wave • the shorter the wavelength, the more energy the wave has

  11. shorter wavelength = more energy higher amplitude = more energy

  12. Frequency – the number of waves produced in a given amount of time; measured in hertz (Hz) • 1 Hz = 1 wave per second • frequency and wavelength are inversely related, which means as one decreases the other increases (and vice versa) • Wave Speed– the speed at which a wave travels • to calculate: wave speed (s) = frequency (f) x wavelength (λ) s = f xλ

  13. higher frequency = shorter wavelength = more energy

  14. Wave Speed Calculations • 1) Determine the wave speed of a wave that has a wavelength of 5 m and a frequency of 4 Hz. s = f xλ= 4 Hz x 5m = 20 m/s • 2) What is the speed of a wave that has a wavelength of 2 m and a frequency of 6 Hz? • 3) What is the frequency of a wave if the wave has a speed of 12 cm/s and a wavelength of 3 cm?

  15. Wave Speed Calculations 2) What is the speed of a wave that has a wavelength of 2 m and a frequency of 6 Hz? s = f x λ s= 6 Hz x 2m s= 12 m/s 3) What is the frequency of a wave if the wave has a speed of 12 cm/s and a wavelength of 3 cm? s = f x λ 12 cm/s= f x 3cm f= 4 Hz

  16. WRITING RESPONSE • When comparing a category 3 hurricane and a category 5 hurricane, which hurricane will create water waves with the most amplitude? Why?

  17. WRITING RESPONSE • When comparing a category 3 hurricane and a category 5 hurricane, which hurricane will create water waves with the most amplitude? Why? A category 5 hurricane will create water waves with the most amplitude because it carries more energy

  18. WAVE INTERACTIONS

  19. Wave Interactions • Absorption – the transfer of energy by a wave to the medium through which it travels • ex. air absorbs sound, dark objects absorb light • Transmission – the passage of light through an object, like a window

  20. Reflection – the bouncing of a wave off a surface • ex. sound wave reflection is called an echo • Normal – line perpendicular to the surface • Angle of Incidence – angle between the incoming wave and the normal • Law of Reflection - when a wave is reflected from a surface, the angle of the reflection is equal to the angle of incidence

  21. Wave Interactions • Refraction – the change in direction of a wave that occurs as the wave changes speed when moving from one medium to another • ex. light waves are refracted when they pass from air to rain drops, and a rainbow is formed

  22. Wave Interactions • Diffraction – the change in direction of a wave when it travels by the edge of an object or through an opening • ex. music around a corner

  23. Wave Interactions • Interference – occurs when waves that overlap combine, forming a new wave • Constructive Interference – when two crests or two troughs combine, therefore combining the energy, and making a larger crest or trough • Destructive Interference – when the crest of one wave meets the trough of another wave, resulting in no wave at all • Standing Wave – two waves of the same wavelength overlap and the wave seems to be standing still

  24. WRITNG RESPONSE How do waves change as they pass from one medium to another? Compare and contrast reflection, refraction, and diffraction.

  25. WRITNG RESPONSE How do waves change as they pass from one medium to another? Waves bend or change direction because their speed changes as they pass through one medium to another Compare and contrast reflection, refraction, and diffraction. Reflection, refraction, and diffraction are all ways waves interact with matter. Reflection occurs when a wave strikes a surface and bounces off. Refraction occurs when a wave changes direction as it passes from one medium to another. Diffraction occurs when waves change direction as they pass by the edge of an object or through an opening.

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