2Wave EnergyWave-any disturbance that transfers energy from one place to another without transferring mattertransfer energy AWAY from the source of the energyMedium – material through which wave energy is transferredwaves travel fastest through solids because molecules are closer together
3Mechanical WavesMechanical 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)
4Mechanical Waves - Transverse Transverse Waves:the disturbance is perpendicular to the direction the wave travelsmove in an up-and-down motiontop of the wave is called the crest and the base of the wave is called the trough
5Mechanical Waves - Longitudinal Longitudinal Wavesthe disturbance moves parallel to the direction the wave travelsmove in a back-and-forth motionwhere particles are crowded together is called the compression, where they are farther apart is called the rarefaction
6Mechanical Waves – Orbital Orbital Waves-(Surface waves)combination of a transverse wave and a longitudinal waveocean waves are an example of surface wavesthe water moves up and down while the wave energy moves forwardobjects in an ocean wave bob up and down in a circular motion
7WRITING RESPONSEWhat do waves transfer from place to place? What kind of materials can mechanical waves move through?
9Electromagnetic (EM) Waves Electromagnetic Waves (EM) – can travel through empty space and through matter; does NOT need a mediumAll electromagnetic waves are transverseex. light waves, x-rays, ultraviolet waves, microwaves, radio wavesThe type of EM waves given off by an object depends mainly on the temperature of the objectEx: humans give off infrared rays
11Amplitude – the height of a wave, from resting position to crest the larger the amplitude, the more energy the wave hasWavelength – distance from any point on a wave to an identical point on the next wavethe shorter the wavelength, the more energy the wave has
12shorter wavelength = more energy higher amplitude = more energy
13Wave Speed – the speed at which a wave travels Frequency – the number of waves produced in a given amount of time; measured in hertz (Hz)1 Hz = 1 wave per secondfrequency and wavelength are inversely related, which means as one decreases the other increases (and vice versa)Wave Speed – the speed at which a wave travelsto calculate: wave speed (s) = frequency (f) x wavelength (λ)s = f x λ
14higher frequency = shorter wavelength = more energy
15Wave 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 x λ = 4 Hz x 5m = 20 m/s2) 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?
16Wave 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 λs= 6 Hz x 2ms= 12 m/s3) What is the frequency of a wave if the wave has a speed of 12 cm/s and a wavelength of 3 cm?12 cm/s= f x 3cmf= 4 Hz
17WRITING RESPONSEWhen comparing a category 3 hurricane and a category 5 hurricane, which hurricane will create water waves with the most amplitude? Why?
18WRITING RESPONSEWhen 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
20Wave InteractionsAbsorption – the transfer of energy by a wave to the medium through which it travelsex. air absorbs sound, dark objects absorb lightTransmission – the passage of light through an object, like a window
21Reflection – the bouncing of a wave off a surface ex. sound wave reflection is called an echoNormal – line perpendicular to the surfaceAngle of Incidence – angle between the incoming wave and the normalLaw of Reflection - when a wave is reflected from a surface, the angle of the reflection is equal to the angle of incidence
23Wave InteractionsRefraction – the change in direction of a wave that occurs as the wave changes speed when moving from one medium to anotherex. light waves are refracted when they pass from air to rain drops, and a rainbow is formed
24Wave InteractionsDiffraction – the change in direction of a wave when it travels by the edge of an object or through an openingex. music around a corner
25Wave InteractionsInterference – occurs when waves that overlap combine, forming a new waveConstructive Interference – when two crests or two troughs combine, therefore combining the energy, and making a larger crest or troughDestructive Interference – when the crest of one wave meets the trough of another wave, resulting in no wave at allStanding Wave – two waves of the same wavelength overlap and the wave seems to be standing still
26WRITNG RESPONSEHow do waves change as they pass from one medium to another? Compare and contrast reflection, refraction, and diffraction.
27WRITNG RESPONSEHow 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 anotherCompare 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.