Chapter Menu Chapter Introduction Lesson 1Lesson 1Waves Lesson 2Lesson 2Light Lesson 3Lesson 3Sound...

Chapter Introduction

Lesson 1 Waves

Lesson 2 Light

Lesson 3 Sound

Chapter Wrap-Up

How do waves transfer energy through matter and through empty space?

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What do you think?

Before you begin, decide if you agree or disagree with each of these statements. As you view this presentation, see if you change your mind about any of the statements.


1. Waves carry matter from place to place.

2. All waves move with an up-and-down motion.

3. Light is the only type of wave that can travel through empty space.

4. Only shiny surfaces reflect light.

Do you agree or disagree?


5. Sound travels faster through solid materials than through air.

6. The more energy used to produce a sound, the louder the sound.



• What are waves, and how are waves produced?

• How can you describe waves by their properties?

• What are some ways in which waves interact with matter?

Waves


• mechanical wave

• electromagnetic wave

• transverse wave

• longitudinal wave

Waves

• frequency

• amplitude

• refraction


• A. What are waves?

• 1. All waves begin with a source of energy that causes a back-and-forth or up-and-down disturbance, or movement.

• 2. A(n) wave is a disturbance that transfers energy from one place to another without transferring matter.

What are waves?


3. When a flag waves in the wind, the flag ripples back and forth as the energy travels along the flag, but the fabric does notmove forward with the wave energy.

What are waves? (cont.)


• 4. A(n) mechanical wave travels only through matter.

• A mechanical wave forms when a source of energy causes particles of matter to vibrate.


Don Farrall/Getty Images


• 5. A(n) electromagnetic wave can travel through empty space or throughmatter.

• An electromagnetic wave forms when a charged particle vibrates.

• The energy that an electromagnetic wave carries is partly electric and partly magnetic.




• 6. There are three types of wave motion—transverse, longitudinal, and a combination of both.


• a. A(n) transverse wave is a wave in which the disturbance is perpendicular to the direction the wave travels.

• High points on the wave are called crests, and low points are called troughs.


• b. A(n) longitudinal wave is a wave that makes the particles of a medium move back and forth parallel to the direction the wave travels.


Longitudinal waves are mechanical waves because this type of motion can occur only when energy passes from particle to particle.


• 7. Two common waves in nature are water waves andseismic waves.

• a. In water waves, water particles move in circles, indicating that these waves are a combination of longitudinal andtransverse waves.


• b. Seismic waves occur during an earthquake.


B. Properties of Waves

• 1. The wavelength of a wave is the distance from one point, suchas the crest, to the corresponding point on the next wave.

• 2. The frequency of a wave is the number of wavelengths that passa point each second.

Properties of Waves


• 3. Frequency is measured in hertz (Hz); the longer the wavelength, the lower the frequency.

• 4. Wave speed depends on the type of material, or medium, a wavetravels through.

Properties of Waves (cont.)


• 5. The maximum distance a wave varies from its rest position is the amplitude of the wave; the more energy a(n)mechanical wave has, the larger thewave’s amplitude will be.

Properties of Waves (cont.)


The more energy used to produce a mechanical wave, the farther a particle of the medium vibrates from its rest position.


• C. Wave Interaction with Matter

• 1. When you knock on one side of a door, the sound travels aslongitudinal sound waves through the door.

• 2. These waves travel through the matter that makes up the doorto the air on the other side.

Wave Interaction with Matter


• 3. The particles that make up the door absorb some of the sound energy; they increase their motion, changing to thermal energy. This causes a(n) decrease in the sound.

• 4. Some of the energy of your knock bounces, or reflects, back into the room; that is why you hear the sound.


• 5. Waves that bounce off a surface follow the law of reflection: theangle between the incident (incoming) wave and the normal (the perpendicular to the surface) is equal to the angle between the reflected wave and the normal.


• 6. Refraction is the change in direction of a wave as it changes speed, moving from one medium into another.

• 7. When entering a medium, waves refract toward the normal if they slow down and away from the normal if they speed up.


• 8. The change in direction of a(n) wave when it travels past theedge of an object or through an opening is called diffraction;sound waves spread around a(n) corner due to diffraction.


• A wave is a disturbance that transfers energy from one place to another without transferring matter.



• A wave can have a disturbance parallel or perpendicular to the direction the wave travels. Some waves have a combination of the two directions.


• Waves can interact with matter by reflection, refraction, and diffraction.


Which term refers to the maximum distance a wave varies from its rest position?

A. amplitude

B. frequency

C. reflection

D. refraction


A. electromagnetic

B. longitudinal

C. mechanical

D. transverse

Which wave travels only through matter?


A. wavelength

B. medium

C. frequency

D. direction

What does a wave’s speed depend on?


1. Waves carry matter from place to place.

2. All waves move with an up-and-down motion.



• How does light differ from other forms of electromagnetic waves?

• What are some ways in which light interacts with matter?

• How do your eyes change light waves into the images you see?

Light


• radio wave

• infrared wave

• ultraviolet wave

• transparent

Light

• translucent

• opaque

• intensity


• A. What are light waves?

• 1. Light is a small range of electromagnetic waves that aredetected by most people’s eyes.

• 2. Objects that produce light, including the Sun and light bulbs, areluminous objects.

What are light waves?


• B. The Electromagnetic Spectrum

• 1. There are seven main types of waves that make up the electromagnetic spectrum; these waves have differentwavelengths, frequencies, and energy.

The Electromagnetic Spectrum


• 2. The Sun produces energy that is carried outward in all directions as electromagnetic waves.

• 3. More than 90 percent of the Sun’s energy that reaches Earth is carried bylight and infrared waves.

The Electromagnetic Spectrum (cont.)


A low-frequency, low-energy electromagnetic wave that has a wavelength longer than about 30 cm is called a radio wave


Microwaves range from about 1 mm to 30 cm and are used to cook food, carry cell phone signals, and transmit information by satellites.


An electromagnetic wave that has a wavelength shorter than a microwave but longer than light is called an infrared wave.


An electromagnetic wave that has a slightly shorter wavelength and higher frequency than light is an ultraviolet wave


An electromagnetic wave that has a slightly shorter wavelength and higher frequency than an ultraviolet wave is called an X-ray.


• C. Speed, Wavelength, and Frequency

• 1. The speed of light in empty space is 3 × 108 m/s.

Speed, Wavelength, and Frequency


• 2. The wavelength and the frequency of light determines the color of the light.

• a. The light color that has the longest wavelength and the lowest frequency is red.

• b. Colors at the violet end of the spectrum have the shortest wavelength and the highest frequency.

Speed, Wavelength, and Frequency(cont.)


• D. Light and Matter Interact

• 1. A(n) transparent material allows almost all the light that strikes itto pass through; objects can be seen clearly through this material.

Light and Matter Interact


• 2. A(n) translucent material allows most of the light that strikes it to pass through; objects appear blurry through this material.

• 3. Light does not pass through opaque material.

Light and Matter Interact (cont.)


• 4. You see a clear reflective image when rays reflect from a(n) smooth surface.

• 5. Light interacts with different types of matter in different ways; some of the light is reflected, and some is transmitted or absorbed.


• E. Color

• 1. Colors people see are due to the wavelength of the light that enters their eyes; with a(n) luminous object, the colors are the wavelengths emitted by the object.

Color


• 2. Objects that are opaque absorb all of the wavelengths of light except the wavelengths of the color that people see when white light hits theobject; so the color of an opaque object is the color of the light that the object reflects.

• 3. The color of a transparent or translucent object is the color theobject transmits.


• F. Intensity of Light

• 1. Intensity is the amount of energy that passes through 1 m2 of space in 1 second.

• 2. Intensity varies with distance from the light source; the closer the source, the greater the intensity of the light.

• 3. Brightness is a person’s perception of the light intensity.

Intensity of Light


• G. Interaction of Sunlight and Matter

• 1. Particles that make up the air scatter the blue wavelengths of light more than they scatter longer wavelengths.

• 2. Refraction of sunlight causes the Sun to be visible even after it hasset below Earth’s horizon.

Interaction of Sunlight and Matter


• H. Vision and the Eye

• 1. Light enters the eye through the cornea which, along with thelens, focuses light onto the retina.

• 2. Cells in the retina absorb light and send signals about the light to the brain.

Vision and the Eye


• The different types of electromagnetic waves play important roles in your life.


• Materials transmit, absorb, and reflect different amounts of light.


• Interaction with matter produces interesting effects in sunlight. You can see the Sun even after it sets below the horizon.


What happens when light traveling at an angle passes from one medium into another?

A. The light is reflected.

B. The light is refracted.

C. The lights always speeds up.

D. The light always slows down.


A. blue

B. red

C. violet

D. yellows

Which color has the longest wavelengths and lowest frequencies of light?


A. opaque

B. radiant

C. translucent

D. transparent

Which describes a material through which light does not pass?


3. Light is the only type of wave that can travel through empty space.

4. Only shiny surfaces reflect light.



• What are some properties of sound waves?

• How do your ears enable you to hear sounds?

Sound


• compression

• rarefaction

• pitch

• decibel

Sound


• Sound waves are longitudinal mechanical waves that must travel through a medium.

• Sound waves are vibrations that the ear can detect.

• The human ear is most sensitive to frequencies between 1,000 and 4,000 Hz.

What are sound waves?


• The sound waves you hear usually travel to your ears through air.

• Air particles are in constant motion.

• As the particles bounce off you and other objects, they exert a force, or pressure.

• Sound waves moving through air change the air pressure by causing air particles to move toward and then away from each other.

What are sound waves? (cont.)


A compression is the region of a longitudinal wave where the particles in the medium are closest together.



A rarefaction is the region of a longitudinal wave where the particles are farthest apart.



• A sound wave can be described by its wavelength, frequency, amplitude, and speed.

• Many properties of sound waves depend on their compressions and rarefactions.

Properties of Sound Waves


• The perception of how high or low a sound seems is called pitch.

• The higher the frequency, the higher the pitch of the sound.

Properties of Sound Waves (cont.)


• The more energy you put into your voice, the farther the particles in the air move as they vibrate.

• The distance a vibrating particle moves from its rest position is the amplitude.

• The more energy used to produce the sound wave, the greater the amplitude.




rest position

Science Use position of an undisturbed particle; particles are still in motion here

Common Use the state of something not moving


• Sound waves travel much more slowly than electromagnetic waves because with sound, the transmitted energy must pass from particle to particle.

• The type of medium and the temperature affect the speed of sound.



• A gas takes longer to transfer sound energy between particles.

• Particles move faster and collide more often as the temperature of a gas increases.




What are some properties of sound waves?


• The farther you move from the source, the less energy is present in the same area of space.

• Loudness is your ear’s perception of intensity.




• The unit used to measure sound intensity or loudness is the decibel (dB).

• Each increase of 10dB results in a sound seeming twice as loud.



decibel

from Latin decibus, means “tenth”


• The part of the human ear that you can see, called the outer ear, collects sound waves.

• The middle ear includes the eardrum and three tiny bones called the hammer, the anvil, and the stirrup. The middle ear amplifies the intensity of sound waves.

• The inner ear contains the cochlea, which changes the sound waves to nerve signals that the brain can interpret.

Hearing and the Ear


Hearing and the Ear (cont.)

How do your ears enable you tohear sounds?


• Sounds are produced when an energy source causes matter to vibrate.


• Sound waves are compressions and rarefactions that move away from a sound source.


• You hear sounds when your ears capture sound waves and produce signals that travel to your brain.


Which term refers to the distance a vibrating particle moves from its rest position?

A. amplitude

B. decibel

C. frequency

D. pitch


A. the cochlea

B. the inner ear

C. the middle ear

D. the outer ear

Which part of the ear includes the eardrum, the hammer, the anvil, and the stirrup?


A. air

B. steel

C. water

D. outer space

Through which medium does sound travel fastest?


5. Sound travels faster through solid materials than through air.

6. The more energy used to produce a sound, the louder the sound.



Key Concept Summary

Interactive Concept Map

Chapter Review

Standardized Test Practice

Mechanical waves transfer energy from particle to particle in matter. Electromagnetic waves transfer energy through either matter or empty space.

• Waves are disturbances that transfer energy from place to place. A mechanical wave forms when a source of energy causes particles of matter to vibrate. A vibrating electric charge produces an electromagnetic wave.

• You can describe the wavelength, frequency, speed, amplitude, and energy of waves.

• Matter can transmit, absorb, or reflect a wave. It also can change a wave’s direction by refraction or diffraction.

Lesson 1: Waves


Lesson 2: Light

• Light differs from other forms of electromagnetic waves by its frequency, wavelength, and energy. Light is the type of electromagnetic wave that people can see.

• Matter can transmit, absorb, and reflect light. These interactions differ in how much light the matter transmits and how it changes the direction of light.

• Cells on the retina of your eye change light into electric signals that travel to your brain.

• Sound waves travel through matter as a series of compressions and rarefactions. The frequency and wavelength of a sound wave determines the pitch. Sound waves with greater amplitude sound louder.

• Your ears collect and amplify sound and then convert it to signals that your brain can interpret.

Lesson 3: Sound

A. refraction

B. reflection

C. diffraction

D. amplitude

Which term refers to the change in direction of a wave as it changes speed in moving from one medium to another?


A. amplitude

B. diffraction

C. frequency

D. medium

Which describes the number of wavelengths that pass a point each second?


A. translucent

B. transparent

C. opaque

D. intensity

Which describes materials through which light does not pass through?


A. X-rays

B. ultraviolet wave

C. radio wave

D. gamma rays

Which refers to electromagnetic waves produced by vibrations within the nucleus of an atom?


A. amplitude

B. decibel

C. frequency

D. pitch

Which refers to the unit used to measure sound intensity or loudness?


A. crest

B. frequency

C. trough

D. wavelength

Which term refers to the distance between a point on one wave and the same point on the next wave?


A. electromagnetic

B. longitudinal

C. mechanical

D. transverse

What type of wave makes the particles in a medium move back and forth along the direction the wave travels?


A. ultraviolet

B. radio

C. microwaves

D. gamma

Which waves are used to cook food, carry cell phone signals, and transmit information by satellites?


A. transparent

B. translucent

C. radiant

D. opaque

Which material allows most of the light that strikes it to pass through but forms a blurry image?


A. compression

B. pitch

C. rarefaction

D. vibration

In which region of a longitudinal wave are the particles in the medium closest together?


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