2Big Ideas1.1 Waves Transfer energy1.2 Waves have measurable properties1.3 Waves behave in predictable ways.
3The Nature of WavesWhat is a wave?A wave is a repeating disturbance or movement that transfers energy through matter or space
4Waves transfer energy not matter. The water waves below are carrying energy but are not moving. Waves can only exist as they have energy to carry.
5*Mechanical waves are waves which require a medium. A medium is a form of matter through which the wave travels (such as water, air, glass, etc.)*Waves such as light, x-rays, and other forms of radiation do not require a medium.
6What are the two kinds of mechanical waves? TransverseLongitudinal
7Transverse WavesIn a transverse wave the matter in the wave moves up and down at a right angle to the direction of the waveTransverse waves— The motion of particles is at 900 anglesExample – rope, water waves, light waves
9Water waves transfer energy through matter (mechanical waves): Particles of water move around in circles. The farther below the surface,the smaller the circle.
10Also called compression waves Longitudinal WavesIn a longitudinal wave the matter in the wave moves back and forth, parallel to the direction of the wave.Observe the red lineAlso called compression waves
11You can see the result of vibrations that create motion in the water to produce waves on the beach. As the wave slows, its crest and trough come closer together. The top of the wave is not slowed by friction and moves faster than the bottom.
12Longitudinal vs. Transverse Waves Sound05/02/2006Longitudinal vs. Transverse WavesSound is a longitudinal wave, meaning that the motion of particles is along the same direction of the forceLecture 10
13What are earthquake waves (seismic waves)? An energy wave that--vibrates through the earth’s crust as the crust bends or breaks.--seismic waves produce both transverse and longitudinal waves.--Some travel through the earth and some travel across the earth’s surface.
14Anatomy of a Seismic Wave When the Earth’s crust breaks, energy that isreleased transmits outward, causing anearthquake. Some waves travel through the earthand some travel across the earth’s surface.
15longitudinal, sound waves and seismic waves have in common? What do transverse,longitudinal, sound waves and seismic waves have in common?They all must travel through a MEDIUM…..any matter (air, water, ground)Electromagnetic waves DO NOT require a medium.
16Examples of electromagnetic waves Radio wavesMicrowavesinfrared wavesultraviolet light (UV light from sun)X-raysgamma-rays
17What are the parts of a transverse wave? The crest is the highest point on a transverse wave.The trough is the lowest point on a transverse wave.The rest position or fixed position of the wave is called the node or nodal line.
18What is a wavelength?The wavelength is the distance from one crest to another crest or the distance from one trough to another trough.
19Parts of a waveWave heightWavelengthCrestCrestTrough
20Longitudinal (Compressional) wave On a longitudinal wave the area squeezed together is called the compression.The areas spread out are called the rarefaction.
21Longitudinal (compressional) wave The wavelength is the distance from the center of one compression to the center of the next compression.
22Important Wave TermsWavelength (λ) is a measure of distance, so the units for wavelength are always distance units, such as meters, etcFrequency (f) is the number of waves that pass through a point in one second. The unit for frequency is waves per second or Hertz (Hz). One Hz = One wave per secondThe amplitude of a wave is directly related to the energy of a wave
23How are Frequency and Wavelength Related? The smaller the wavelength, the more times it will pass through a point in one second. The larger the wavelength, the fewer times it will pass through a point in one second.Period is the time it takes for one full wavelength to pass a certain point.
24The amplitude in a longitudinal wave depends on how dense the medium is at each compressionHigh amplitudeLow amplitudeAB.
25What is amplitude?The amplitude of a transverse wave is determined by the height of the crest or depth of the trough.
26The Behavior of WavesWhat is reflection?When a wave bounces off an object and changes direction – this is reflection.
27What is refraction?Refraction is the bending of a wave as it passes from one medium to another.A wave travels at different speeds in different things. When a wave traveling a certain speed moves into another medium, it will either increase in speed or decrease in speed, resulting in a change in direction.The pencil looks like it is broken at thesurface of the water because of Refraction
28If you are in a swimming pool under water and look up and saw a ball, Is the ball really directly above you?
34Warm up Name, Date - 2/20/1011How many centimeters (cm) are on the graph? Each green mark on thehorizontal line represents a cm.2. How many cm did the wave travel?3. How many wavelengths are on the graph?