Waves

1. Waves Chapter 14

2. 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.

3. 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.

4. 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.

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

6. 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.

7. 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.

8. In which type of a wave does the particles travel perpendicular to the direction of the wave? • longitudinal • transverse • surface • none of the above

9. What is the top part of a wave called? • amplitude • compression • crest • trough

10. What do we call is the distance between two crest on a transverse wave? • amplitude • frequency • period • wavelength

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

12. Wave Speed • wave speed=frequency x wavelength • V=f x λ

13. 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.

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

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

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

17. A transverse wave….. • Vibrates particles perpendicular to the direction of wave • Vibrates particles parallel to the direction of the wave • Vibrates both parallel and perpendicular to the direction of the wave • Vibrates particles in one direction • I don’t get it.

18. In the diagram, identify the wave property “A” • Frequency • Amplitude • Wavelength • I don’t know

19. 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.

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

21. 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.

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

23. 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.

24. 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.

25. 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.

26. Longitudinal Wave

27. Transverse

28. Water Wave

29. Rayleigh Surface Wave

30. 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

31. 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

32. 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

33. 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

34. 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

35. 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

36. 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

37. 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

38. 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

39. 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

40. 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

41. Internet Cites • http://id.mind.net/~zona/mstm/physics/waves/interference/waveInterference2/WaveInterference2.html • http://id.mind.net/~zona/mstm/physics/waves/interference/waveInterference1/WaveInterference1.html • http://id.mind.net/~zona/mstm/physics/waves/partsOfAWave/waveParts.htm • http://micro.magnet.fsu.edu/primer/java/wavebasics/index.html • http://www.bbc.co.uk/schools/gcsebitesize/physics/waves/an_introduction_to_wavesrev4.shtml