1 Waves Chapter 14

2 Wave at the Shoe

3 Types of Waves A wave is a disturbance that carries energy through matter or space. The medium is the matter through which a wave travels. Waves that require medium are called mechanical waves.

4 What is the wave called when it requires a medium? A. mechanical B. longitudinal C. surface D. transverse

5 Transverse waves Transverse waves are waves which the motion of the particles is perpendicular to the motion of the wave. The top of the wave is called the crest. The bottom of the wave is called the trough. The distance between the crest on one wave to the crest on the next is called the wavelength.

6 Longitudinal wave Longitudinal waves are waves where the particles in the medium vibrate parallel to the direction of the wave motion. Compressions are the parts of the wave where the medium is compressed. Rarefactions are parts of the wave where the medium is spread apart. The distance between compressions is the wavelength.

7 Surface waves Surface waves occur at the boundary between two mediums. The particles move both perpendicularly and parallel.

8 Which type of wave motion of the particles is perpendicular to the motion of the wave? 1. longitudinal. 2. seismic. 3. surface. 4. transverse. :

9 Wave Properties(continued) Wavelength is the distance from one crest to the crest of the next wave. Period is the time required for one full wavelength of a wave to pass a certain point. Frequency of a wave is the number of full wavelengths that pass a point in a given time interval.

10 Wave Properties Transverse waves have the shape of a sine curve. Highest point of a transverse wave is a crest. Lowest point of a transverse wave is a trough. Amplitude is the greatest distance that particles are displaced from their normal resting position.

11 In which type of a wave does the particles travel perpendicular to the direction of the wave? 1. longitudinal 2. transverse 3. surface 4. none of the above

12 What is the top part of a wave called? 1. amplitude 2. compression 3. crest 4. trough

13 What do we call is the distance between two crest on a transverse wave? 1. amplitude 2. frequency 3. period 4. wavelength

14 Frequency-Period Equation Frequency=1/period F=1/T Frequency is measured in a unit called a hertz.

15 Wave Speed wave speed=frequency x wavelength v = f x λ

16 What unit is frequency measured? A. joules B. hertz C. meters D. newtons :

17 Doppler Effect The Doppler Effect is the changed in the observed frequency of a wave resulting from the motion of the source or observer. As the source is approaching the observer, the wavelength decreases and the pitch increases. As the source is going away from the observer, the wavelength increases and the pitch decreases.

18 Doppler Effect

19 As a fire truck approaches you, what happens to the sound? 1. pitch increases. 2. wavelength decreases. 3. sound gets louder. 4. all the above. :

20 Reflection Reflection is the bouncing back of a wave when it meets a surface or boundary.

21 Diffraction Diffraction is when a wave bends around an object or opening.

22 Refraction Refraction is the bending of a wave as it passes from one medium to another medium.

23 A transverse wave….. A. Vibrates particles perpendicular to the direction of wave B. Vibrates particles parallel to the direction of the wave C. Vibrates both parallel and perpendicular to the direction of the wave D. Vibrates particles in one direction E. I don’t get it. :

24 In the diagram, identify the wave property “A” A. Frequency B. Amplitude C. Wavelength D. I don’t know :

25 What type of a wave interaction involves a wave bending as it passes from one medium into another? 1. diffraction 2. reflection 3. refraction 4. I don’t know :

26 Wave Interference Wave interference is when several waves are in the same location and the waves combine to produce a single, new wave that is different from the original waves.

27 Constructive Interference The result of two individual waves coming together to produce a wave of greater amplitude is called constructive interference.

28 Destructive Interference The result of two individual waves coming together to produce a wave of lesser amplitude than the larger of the original waves is called destructive interference.

29 Interference As two wave sources combine, the waves pattern changes.

30 Beats Interference of sound waves produces beats. The beat frequency refers to the rate at which the volume is heard to be oscillating from high to low volume.

31 Standing Waves Standing wave is when the interference of the original wave with the reflected wave causes the medium to vibrate in a stationary pattern.

32 Standing Wave Nodes are the areas of a standing wave where there are no vibrations. Antinodes are areas of a standing wave where there is maximum vibration.

33 Longitudinal Wave

34 Transverse

35 Water Wave

36 Rayleigh Surface Wave

37 Review Questions Name the three types of waves. transverse, longitudinal & surface Which type of wave has the particles moving perpendicular to the motion of the wave? transverse Which type of wave has the particles moving parallel to the motion of the wave? longitudinal

38 Review Questions Which three things can a wave do when it meets a barrier? reflect, diffract or refract When the crest from one wave meets the crest of another wave, what happens? constructive interference What do you call the top of a transverse wave? crest

39 Review Questions On a longitudinal wave, what do you call the part of the wave that is spread out? rarefaction What is it called when the sound approaching you gets louder and fades as it is going away from you? Doppler Effect

40 Review Questions What happens when the crest of one wave meets the trough of another wave? destructive interference What type of interaction occurs when a wave strikes a barrier and bounces back? reflection

41 Review Questions What is the relationship between wave speed, frequency & wavelength? Wave speed=frequency x wavelength What do we call the interference of waves of slightly different frequencies traveling in the same direction? beat

42 Review Questions What is the bottom part of a transverse wave called? trough What is the part of the longitudinal wave where the wave is pressed closely together? compressions What is the interaction of a wave called where the wave changes speed as it passes from one medium to another and bends? refraction

43 Review Questions What is the distance between two crests on a transverse wave called? wavelength What is the distance between a crest and the resting position called? amplitude What do we call the number of waves that pass a given point in a given amount of time? frequency

44 Review Questions What do we call the time it takes for one wave to move past a given point? period What happens to the frequency of a wave as the wavelength gets longer? lowers In which metric units do we measure frequency? hertz

45 Review Questions What is the material called that waves move through? medium What type of wave needs a medium to move? mechanical What do we call a disturbance that transfers energy? wave

46 Review Questions What type of wave is light? transverse What type of wave is sound? longitudinal What type of wave is produced when a wave is interfered with by its reflected wave? Standing wave

47 Review Questions What is the part of a standing wave called where there are no vibrations? nodes How does the medium affect the wave speed? the closer the particles, the faster the wave speed Where do surface waves occur? boundary between two mediums

48 Internet Cites nce/waveInterference2/WaveInterference2.html nce/waveInterference1/WaveInterference1.html partsOfAWave/waveParts.htm dex.html es/an_introduction_to_wavesrev4.shtml