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2. Standardized Test Prep
Resources
Chapter Presentation
Bellringers
Transparencies
Standardized Test Prep
Math Skills
Visual Concepts

3. Chapter 14 Table of Contents Section 1 Types of Waves
Section 2 Characteristics of Waves
Section 3 Interactions of Waves

4. Chapter 14 Objectives Recognize that waves transfer energy.
Section 1 Types of Waves
Objectives
Recognize that waves transfer energy.
Distinguish between mechanical waves and electromagnetic waves.
Explain the relationship between particle vibration and wave motion.
Distinguish between transverse waves and longitudinal waves.

5. Chapter 14
Section 1 Types of Waves
Bellringer
Imagine throwing a rock into a pond or lake. Describe the effect that the rock has on the surface of the water.
When surfing, a person moves just ahead of a wave. Where does the energy come from to move the surfer through the water?
What happens to a string on a guitar or other stringed instrument when it is plucked?
When a musician strikes two cymbals together, the cymbals will begin to vibrate and make music. How does the musician stop the music?

6. Chapter 14
Section 1 Types of Waves
What Is a Wave?
A wave is a periodic disturbance in a solid, liquid, or gas as energy is transmitted through a medium.
Waves carry energy through matter or space.
Most waves travel through a medium.
The matter through which a wave travels is called the medium.
Waves that require a medium are called mechanical waves.

7. Formation and Movement of Ocean Waves
Chapter 14
Section 1 Types of Waves
Formation and Movement of Ocean Waves

8. What Is a Wave?, continued
Chapter 14
Section 1 Types of Waves
What Is a Wave?, continued
Light does not require a medium.
Light waves consist of changing electric and magnetic fields in space.
Light waves are called electromagnetic waves.
An electromagnetic wave consists of oscillating electric and magnetic fields, which radiate outward at the speed of light.

9. Electromagnetic Waves
Chapter 14
Section 1 Types of Waves
Electromagnetic Waves

10. What Is a Wave?, continued
Chapter 14
Section 1 Types of Waves
What Is a Wave?, continued
Waves transfer energy.
Energy may spread out as a wave travels.
When sound waves travel in air, the waves spread out in spheres. As they travel outward, the spherical wave fronts get bigger, so the energy in the waves spreads out over a larger area.

11. Chapter 14
Section 1 Types of Waves
Tsunami

12. Chapter 14 Vibrations and Waves Waves are related to vibrations.
Section 1 Types of Waves
Vibrations and Waves
Waves are related to vibrations.
Most waves are caused by a vibrating object.
Electromagnetic waves may be caused by vibrating charged particles.
In a mechanical wave, the particles in the medium also vibrate as the wave passes through the medium.
Vibrations involve transformations of energy.

13. Chapter 14
Section 1 Types of Waves
Wave Model

14. Vibrations and Waves, continued
Chapter 14
Section 1 Types of Waves
Vibrations and Waves, continued
Whenever a spring is expanded or compressed, it is exerting a force that pushes the mass back almost to the original resting position.
As a result, the mass will continue to bounce up and down.
This type of vibration is called simple harmonic motion.
A wave can pass through a series of vibrating objects.

15. Chapter 14
Section 1 Types of Waves
Wave Model

16. Vibrations and Waves, continued
Chapter 14
Section 1 Types of Waves
Vibrations and Waves, continued
If the first mass were not connected to the other masses, it would keep vibrating up and down on its own. However, because it transfers its energy to the second mass, it slows down and then returns to its resting position.
A vibration that fades out as energy is transferred from one object to another is called damped harmonic motion.
The motion of particles in a medium is like the motion of masses on springs.

17. Transverse and Longitudinal Waves
Chapter 14
Section 1 Types of Waves
Transverse and Longitudinal Waves
Particles in a medium can vibrate either up and down or back and forth.
Waves are often classified by the direction that the particles in the medium move as a wave passes by.
Transverse waves have perpendicular motion.
A transverse wave is a wave in which the particles of the medium move perpendicular to the direction the wave is traveling.
Light waves are transverse waves.

18. Chapter 14
Section 1 Types of Waves
Transverse Wave

19. Transverse and Longitudinal Waves
Chapter 14
Section 1 Types of Waves
Transverse and Longitudinal Waves
Longitudinal waves have parallel motion.
A longitudinal wave is a wave in which the particles of the medium vibrate parallel to the direction of wave motion.
Sound waves are longitudinal waves.
In a surface wave, particles move in circles.
Surface waves occur at the boundary between two different mediums, such as between water and air.
The particles move both perpendicularly and parallel to the direction that the wave travels.

20. Chapter 14
Section 1 Types of Waves
Longitudinal Wave

21. Chapter 14
Section 1 Types of Waves
Water Wave Motion

22. Section 2 Characteristics of Waves
Chapter 14
Objectives
Identify the crest, trough, amplitude, and wavelength of a wave.
Define the terms frequency and period.
Solve problems involving wave speed, frequency, and wavelength.
Describe the Doppler effect.

23. Chapter 14 Bellringer Section 2 Characteristics of Waves
There are many different types of waves. You may be familiar with the electromagnetic spectrum, which includes radio waves, microwaves, infrared light, visible light, ultraviolet light, X rays, and gamma rays.
Name five common applications of waves in the electromagnetic spectrum, and list the type of wave used in each case.
Lasers are made from accurately focused visible light waves that are produced in phase with each other. Lasers made from visible light waves are often used in surgery to perform delicate procedures and to seal the area being treated. Write a paragraph describing how you think this process works.

24. Section 2 Characteristics of Waves
Chapter 14
Wave Properties

25. Chapter 14 Wave Properties
Section 2 Characteristics of Waves
Chapter 14
Wave Properties
An ideal transverse wave has the shape of a sine curve.
Waves that have the shape of a sine curve are called sine waves.

26. Wave Properties, continued
Section 2 Characteristics of Waves
Chapter 14
Wave Properties, continued
Amplitude measures the amount of particle vibration.
The crest is the highest point of a transverse wave.
The trough is the lowest point of a transverse wave.
The amplitude is the maximum distance that the particles of a wave’s medium vibrate from their rest position.

27. Characteristics of a Wave
Section 2 Characteristics of Waves
Chapter 14
Characteristics of a Wave

28. Wave Properties, continued
Section 2 Characteristics of Waves
Chapter 14
Wave Properties, continued
A longitudinal wave has compressions and rarefactions.
The crowded areas are called compressions.
The stretched-out areas are called rarefactions.
The amplitude of a longitudinal wave is the maximum deviation from the normal density or pressure of the medium.

29. Wave Properties, continued
Section 2 Characteristics of Waves
Chapter 14
Wave Properties, continued
A. A longitudinal wave has compressions and rarefactions.
B. The high and low points of this sine curve correspond to compressions and rarefactions in the spring.

30. Wave Properties, continued
Section 2 Characteristics of Waves
Chapter 14
Wave Properties, continued
Wavelength measures the distance between two equivalent parts of a wave.
The wavelength is the distance from any point on a wave to an identical point on the next wave.
Not all waves have a single wavelength that is easy to measure.
Wavelength is represented by the Greek letter lambda, .

31. Wave Properties, continued
Section 2 Characteristics of Waves
Chapter 14
Wave Properties, continued
The period measures how long it takes for waves to pass by.
The period is the time that it takes a complete cycle or wave oscillation to occur.
The period is represented by the symbol T.
Frequency measures the rate of vibrations.
The frequency is the number of cycles or vibrations per unit of time.
The symbol for frequency is f.
The SI unit for measuring frequency is hertz.

32. Section 2 Characteristics of Waves
Chapter 14
Frequency

33. Wave Period of Ocean Waves
Section 2 Characteristics of Waves
Chapter 14
Wave Period of Ocean Waves

34. Wave Properties, continued
Section 2 Characteristics of Waves
Chapter 14
Wave Properties, continued
The frequency and period of a wave are related.
The frequency is the inverse of the period.

35. Wave Properties, continued
Section 2 Characteristics of Waves
Chapter 14
Wave Properties, continued
Light comes in a wide range of frequencies and wavelengths.
Our eyes can detect light with frequencies ranging from about 4.3  1014 Hz to 7.5  1014 Hz.
Light in this range is called visible light.
The full range of light at different frequencies and wavelengths is called the electromagnetic spectrum.

36. Section 2 Characteristics of Waves
Chapter 14
Visible Light

37. The Electromagnetic Spectrum
Section 2 Characteristics of Waves
Chapter 14
The Electromagnetic Spectrum

38. Chapter 14 Wave Speed Wave speed equals frequency times wavelength.
Section 2 Characteristics of Waves
Chapter 14
Wave Speed
Wave speed equals frequency times wavelength.

39. Equation for the Speed of a Wave
Section 2 Characteristics of Waves
Chapter 14
Equation for the Speed of a Wave

40. Section 2 Characteristics of Waves
Chapter 14
Math Skills
Wave Speed The string of a piano that produces the note middle C vibrates with a frequency of 264 Hz. If the sound waves produced by this string have a wavelength in air of 1.30 m, what is the speed of sound in air?
List the given and unknown values.
Given: frequency, f = 264 Hz
wavelength,  = 1.30 m
Unknown: wave speed,  = ? m/s

41. Chapter 14 Math Skills, continued Write the equation for wave speed.
Section 2 Characteristics of Waves
Chapter 14
Math Skills, continued
Write the equation for wave speed.
= f  
Insert the known values into the equation, and solve.
 = 264 Hz  1.30 m = 264 s−1  1.30 m
 = 343 m/s

42. Chapter 14 Wave Speed, continued
Section 2 Characteristics of Waves
Chapter 14
Wave Speed, continued
The speed of a wave depends on the medium.
In a given medium, though, the speed of waves is constant; it does not depend on the frequency of the wave.
Kinetic theory explains differences in wave speed.
The arrangement of particles in a medium determines how well waves travel through it.
In gases, the molecules are far apart and move around randomly. Waves don’t travel as fast in gases.

43. Chapter 14 Wave Speed, continued Light has a finite speed.
Section 2 Characteristics of Waves
Chapter 14
Wave Speed, continued
In liquids, such as water, the molecules are much closer together. But they are also free to slide past one another.
In a solid, molecules are not only closer together but also tightly bound to each other. Waves travel very quickly through most solids.
Light has a finite speed.
All electromagnetic waves in empty space travel at the same speed, the speed of light, which is
3.00  108 m/s ( mi/s).
Light travels slower when it has to pass through a medium such as air or water.

44. Chapter 14 Doppler Effect
Section 2 Characteristics of Waves
Chapter 14
Doppler Effect
Pitch is determined by the frequency of sound waves.
The pitch of a sound, how high or low it is, is determined by the frequency at which sound waves strike the eardrum in your ear.
A higher-pitched sound is caused by sound waves of higher frequency.
Frequency changes when the source of waves is moving.
The Doppler effect is an observed change in the frequency of a wave when the source or observer is moving.

45. Doppler Effect and Sound
Section 2 Characteristics of Waves
Chapter 14
Doppler Effect and Sound

46. Chapter 14
Section 3 Wave Interactions
Objectives
Describe how waves behave when they meet an obstacle or pass into another medium.
Explain what happens when two waves interfere.
Distinguish between constructive interference and destructive interference.
Explain how standing waves are formed.

47. Chapter 14
Section 3 Wave Interactions
Bellringer
The back of a mirror is flat and highly reflective. Describe how you think a mirror works.
Why do you think one piece of safety equipment that backpackers carry into the wilderness is a mirror?
Describe what an echo is.
Blinds in the windows of homes, schools, and offices can be tilted up or down, or they can be closed completely. Explain how varying positions of the blinds controls light.

48. Reflection, Diffraction, and Refraction
Chapter 14
Section 3 Wave Interactions
Reflection, Diffraction, and Refraction
Reflection is the bouncing back of a ray of light, sound, or heat when the ray hits a surface that it does not go through.
Waves reflect at a free boundary.
The reflected wave is exactly like the original wave except that the reflected wave is traveling in the opposite direction to the direction of the original wave.
At a fixed boundary, waves reflect and turn upside down.

49. Chapter 14
Section 3 Wave Interactions
Reflection

50. Chapter 14
Section 3 Wave Interactions
Reflection

51. Reflection, Diffraction, and Refraction, continued
Chapter 14
Section 3 Wave Interactions
Reflection, Diffraction, and Refraction, continued
Diffraction is the bending of waves around an edge.
Diffraction is a change in the direction of a wave when the wave finds an obstacle or an edge, such as an opening.
Waves can also bend by refraction.
Refraction is the bending of a wavefront as the wavefront passes between two substances in which the speed of the wave differs.
All waves are refracted when they pass from one medium to another at an angle.

52. Chapter 14
Section 3 Wave Interactions
Diffraction

53. Chapter 14
Section 3 Wave Interactions
Refraction

54. Chapter 14
Section 3 Wave Interactions
Interference
Waves in the same place combine to produce a single wave.
Interference is the combination of two or more waves of the same frequency that results in a single wave.
The resulting wave can be found by adding the height of the waves at each point.
Crests are considered positive, and troughs are considered negative.
This method of adding waves is sometimes known as the principle of superposition.

55. Constructive and Destructive Interference
Chapter 14
Section 3 Wave Interactions
Constructive and Destructive Interference

56. Interference, continued
Chapter 14
Section 3 Wave Interactions
Interference, continued
Constructive interference increases amplitude.
Constructive interference is any interference in which waves combine so that the resulting wave is bigger than the original waves.
The amplitude of the resulting wave is the sum of the amplitudes of the two individual waves.
Destructive interference decreases amplitude.
Destructive interference is any interference in which waves combine so that the resulting wave is smaller than the largest of the original waves.
When destructive interference occurs between two waves that have the same amplitude, the waves may completely cancel each other out.

57. Interference, continued
Chapter 14
Section 3 Wave Interactions
Interference, continued
Interference of light waves creates colorful displays.
Interference of sound waves produces beats.
When two waves of slightly different frequencies interfere with each other, they produce beats.

58. Chapter 14 Standing Waves Interference can cause standing waves.
Section 3 Wave Interactions
Standing Waves
Interference can cause standing waves.
A standing wave is a pattern of vibration that simulates a wave that is standing still.
Standing waves can form when a wave is reflected at the boundary of a medium.
Although it appears as if the wave is standing still, in reality waves are traveling in both directions.

59. Chapter 14
Section 3 Wave Interactions
Standing Wave

60. Standing Waves, continued
Chapter 14
Section 3 Wave Interactions
Standing Waves, continued
Standing waves have nodes and antinodes.
Each loop of a standing wave is separated from the next loop by points that have no vibration, called nodes.
Nodes lie at the points where the crests of the original waves meet the troughs of the reflected waves, causing complete destructive interference.
Midway between the nodes lie points of maximum vibration, called antinodes.
Antinodes form where the crests of the original waves line up with the crests of the reflected waves, causing complete constructive interference.

61. Standing Waves, continued
Chapter 14
Section 3 Wave Interactions
Standing Waves, continued
Standing waves can have only certain wavelengths.
In general, standing waves can exist whenever a multiple of half-wavelengths will fit exactly in the length of the string.
It is possible for standing waves of more than one wavelength to exist on a string at the same time.

62. Chapter 14
Section 3 Wave Interactions
Concept Mapping

63. Understanding Concepts
Chapter 14
Standardized Test Prep
Understanding Concepts
1. Which of the following waves can be transmitted without a medium?
A. electromagnetic
B. longitudinal
C. mechanical
D. transverse

64. Understanding Concepts
Chapter 14
Standardized Test Prep
Understanding Concepts
1. Which of the following waves can be transmitted without a medium?
A. electromagnetic
B. longitudinal
C. mechanical
D. transverse

65. Understanding Concepts
Chapter 14
Standardized Test Prep
Understanding Concepts
2. How do longitudinal waves carry energy from a source?
F. Particles vibrate outward from the source of the wave.
G. Particles vibrate parallel to the direction of the wave.
H. Particles vibrate perpendicular to the direction of the wave.
I. Particles vibrate both parallel and perpendicular to the direction of the wave.

66. Understanding Concepts
Chapter 14
Standardized Test Prep
Understanding Concepts
2. How do longitudinal waves carry energy from a source?
F. Particles vibrate outward from the source of the wave.
G. Particles vibrate parallel to the direction of the wave.
H. Particles vibrate perpendicular to the direction of the wave.
I. Particles vibrate both parallel and perpendicular to the direction of the wave.

67. Understanding Concepts
Chapter 14
Standardized Test Prep
Understanding Concepts
3. What is measured by the amplitude of a wave?
A. the amount of vibration of particles
B. the direction of vibration of particles
C. the rate of vibration of particles
D. the wavelength of vibration of particles

68. Understanding Concepts
Chapter 14
Standardized Test Prep
Understanding Concepts
3. What is measured by the amplitude of a wave?
A. the amount of vibration of particles
B. the direction of vibration of particles
C. the rate of vibration of particles
D. the wavelength of vibration of particles

69. Understanding Concepts
Chapter 14
Standardized Test Prep
Understanding Concepts
4. Which combination of wave interactions can cause a standing wave?
F. diffraction and interference
G. diffraction and reflection
H. reflection and interference
I. reflection and refraction

70. Understanding Concepts
Chapter 14
Standardized Test Prep
Understanding Concepts
4. Which combination of wave interactions can cause a standing wave?
F. diffraction and interference
G. diffraction and reflection
H. reflection and interference
I. reflection and refraction

71. Understanding Concepts
Chapter 14
Standardized Test Prep
Understanding Concepts
5. Why do astronauts on the moon need a radio transmitter to carry on a conversation with each other?

72. Understanding Concepts
Chapter 14
Standardized Test Prep
Understanding Concepts
5. Why do astronauts on the moon need a radio transmitter to carry on a conversation with each other?
Answer: Sound waves require a medium to carry energy from one place to another. On the moon, there is no air to carry the vibrations.

73. Chapter 14 Reading Skills
Standardized Test Prep
Reading Skills
The Doppler Effect applies to light as well as sound. Astronomers have used this fact to measure the speed of objects in space as they move away from Earth. They know the frequency and wavelength of the light as it leaves a star because the energy transitions in atoms are the same throughout the universe. When the light reaches Earth, it has a different frequency from when it left the star.
6. Assess how the knowledge that light always travels at the same speed is essential for determining the speed at which a distant galaxy and Earth are moving apart.

74. Chapter 14 Reading Skills
Standardized Test Prep
Reading Skills
6. Assess how the knowledge that light always travels at the same speed is essential for determining the speed at which a distant galaxy and Earth are moving apart.
Answer: Using the change in frequency of light and the fact that the speed of light is constant, astronomers can calculate how fast the objects are moving away from one another.

75. Chapter 14 Reading Skills
Standardized Test Prep
Reading Skills
The Doppler Effect applies to light as well as sound. Astronomers have used this fact to measure the speed of objects in space as they move away from Earth. They know the frequency and wavelength of the light as it leaves a star because the energy transitions in atoms are the same throughout the universe. When the light reaches Earth, it has a different frequency from when it left the star.
7. Astronomers have observed that the wavelength of light reaching Earth from one edge of the sun is slightly different than from the other edge. What can be concluded about the sun based on this observation?

76. Chapter 14 Reading Skills
Standardized Test Prep
Reading Skills
7. Astronomers have observed that the wavelength of light reaching Earth from one edge of the sun is slightly different than from the other edge. What can be concluded about the sun based on this observation?
Answer: The observation indicates that the sun is rotating. The light from one edge is shifted to a shorter wavelength, and light from the other edge is shifted to a longer wavelength.

77. Interpreting Graphics
Chapter 14
Standardized Test Prep
Interpreting Graphics
8. What wave phenomenon is demonstrated in this illustration?
A. diffraction C. reflection
B. Interference D. refraction

78. Interpreting Graphics
Chapter 14
Standardized Test Prep
Interpreting Graphics
8. What wave phenomenon is demonstrated in this illustration?
A. diffraction C. reflection
B. Interference D. refraction

79. Interpreting Graphics
Chapter 14
Standardized Test Prep
Interpreting Graphics
9. Which of the points on the illustration indicates an antinode?
F. W H. Y
G. X I. Z

80. Interpreting Graphics
Chapter 14
Standardized Test Prep
Interpreting Graphics
9. Which of the points on the illustration indicates an antinode?
F. W H. Y
G. X I. Z