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Characteristics of Waves

Chapter 15, pages 472-492

Weekly Target We are learning to demonstrate how waves

transfer energy. We are looking for a disturbance or variation

that transfers energy from on point to another point in a medium. Transverse waves – wave and medium move in

direction that is perpendicular to each other. Longitudinal waves – wave and medium move in

same direction.

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What are Waves? A wave is a disturbance that

transfers energy from place to place

Waves travel through a material called a medium.

Waves that require a medium to travel through are called mechanical waves.

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What are Waves? Waves are created

when a source of energy causes a medium to vibrate.

A vibration is a repeated back-and-forth or up-and –down motion.

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Classification of Waves Wave are classified

according to how they move.

Types of waves:1. Transverse2. Longitudinal3. Surface

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Transverse Wave In transverse waves, the

particles of the medium move perpendicular in the direction of the wave.

Parts of the transverse wave: Crest Trough Wavelength Amplitude

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Longitudinal Wave In longitudinal waves,

the particles of the wave move parallel to direction of the wave movement.

Parts of the wave: Compressions Rarefactions Wavelength

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Surface Wave Surface waves occur at

the boundary between two mediums and are a combination of transverse and longitudinal waves.

A transverse wave…..

Vibrates parti

cles p

erpe...

Vibrates parti

cles p

aralle...

Vibrates both paralle

l a..

Vibrates parti

cles in

one ...

Help! I don’t u

nderstand.

0 0 000

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. Help! I don’t understand.

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What type of wave is represented by picture?

Transverse

Longit

udinal

Surfa

ce

Seism

ic

Help! I don’t u

nderstand.

0 0 000

A. TransverseB. LongitudinalC. SurfaceD. Seismic E. Help! I don’t

understand.

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A wave is a disturbance that transfers

matter.

particle

s.

energy.

a medium.

Help! I don’t u

nderstand.

0 0 000

A. matter.B. particles.C. energy.D. a medium.E. Help! I don’t

understand.

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What do you call the material that a wave travels through?

Plasma

Space

Vacuum

Medium

Help! I don’t u

nderstand.

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A. PlasmaB. SpaceC. VacuumD. MediumE. Help! I don’t

understand.

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What type of wave is represented by the animation?

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A. LongitudinalB. TransverseC. SurfaceD. SeismicE. Help! I don’t understand.

10SecondsRemainin

g

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Transverse WaveDefine (in own Words) Example (from own life)

Picture /Graphic Representation of how this wave transfers energy

Longitudinal WaveDefine (in own Words) Example (from own life)

Picture /Graphic Representation of how this wave transfers energy

We are learning to: describe the properties of waves.

We are looking for: Wavelength-distance from crest to crestFrequency-number of waves that pass a given point each secondAmplitude-distance from rest position to the crest

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Properties of Waves The basic properties of

waves are amplitude, wavelength, frequency, and speed.

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Amplitude Amplitude is the

maximum distance the particles of the medium carrying the wave move away from their rest position.

Measured from crest to resting position.

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Wavelength Wavelength is the

distance between corresponding parts of a wave.

Wavelength is measured from crest to crest.

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Frequency Frequency of a wave is

the number of complete waves that pass a given point in a certain amount of time.

Frequency is measured in hertz.

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Wave Speed Wave speed is how far

the wave travels in one unit of time, or distance divided by time.

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Mathematical Relationship The speed,

wavelength, and frequency of a wave are related to each other by a mathematical formula:

Speed=wavelength x frequency

In the diagram, identify the wave property “A”

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A. FrequencyB. AmplitudeC. WavelengthD. Help! I don’t understand.

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Which of the following is true about waves in the diagram?

Wave X has a

higher fre...

Wave X has a

lower f

re...

Wave X has t

he same fr

...

Help! I don’t u

nderstand.

0 000

A. Wave X has a higher frequency than Wave Y

B. Wave X has a lower frequency than Wave Y

C. Wave X has the same frequency as Wave Y

D. Help! I don’t understand.

:10

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Which of the waves in the picture has the greatest amplitude?

1

2

3

0

0

0

0A. 1

B. 2

C. 3

D. Help! I don’t understand.

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Which property measures the amount of energy transferred by a wave?

Wavelength

Frequency

Amplitude

Help! I don’t u

nderstand.

0 000

A. WavelengthB. FrequencyC. AmplitudeD. Help! I don’t

understand.

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We are learning to demonstrate how waves transfer energy.

We are looking for how waves interact with an object or other waves.  They either:

Transmit-wave energy passes through an object.

Reflect-wave energy bounces off an object.

Absorb-wave energy is taken in by an object they encounter.

Interference-wave energy of multiple waves is combined.

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Interaction of Waves When waves interact,

three things can happen to the waves:

1. Reflect2. Refract3. Diffract

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Reflection Reflection happens when

waves bounce off of a barrier.

The angle of incidence is the angle between the incoming wave and the imaginary perpendicular line.

The angle of reflection is the angle between the reflected wave and the imaginary perpendicular line.

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Law of Reflection The angle of reflection

is equal to the angle of incidence.

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Refraction Refraction occurs as

the wave go between different mediums.

The speed of a wave changes as the medium changes.

The change in speed of the wave causes the waves to bend.

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Diffraction Diffraction is the

bending of waves as the waves go through a small opening or around a corner.

As the wave goes through the hole or around the corner, it spreads out and bends.

What is it called when a wave bounces off of a barrier?

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Diffraction

Reflection

Refracti

on

Help, I don’t .

..

0% 0%0%0%

10A. DiffractionB. ReflectionC. RefractionD. Help, I don’t

understand.

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What happens to waves as they go through an opening or around a corner of an object?

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They are diffr...

They are refle...

They are refra

...

Help, I don’t .

..

0% 0%0%0%

10A. They are diffracted.B. They are reflected.C. They are refracted.D. Help, I don’t

understand.

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As waves go through different mediums, what happens to them?

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Waves c

hange s...

Waves c

hange s...

Waves c

hange s...

Help, I don’t .

..

0% 0%0%0%

1010A. Waves change speed and are diffracted.

B. Waves change speed and are reflected.

C. Waves change speed and are refracted.

D. Help, I don’t understand.

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Interference Interference occurs as two

or more waves interact. Constructive interference

happens when waves meet and the amplitude increases.

Destructive interference happens when waves meet and the amplitude decreases.

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Standing Waves Standing waves form

as the original wave is interfered with by the reflected wave.

The standing wave has a node and an antinode.

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What happens to the energy of the wave What happens to the energy of the wave when the crest of the blue wave meets when the crest of the blue wave meets the crest of the green wave?the crest of the green wave?

Energy

decrease

s.

Energy

incre

ases.

Energy

stays t

he same.

I don’t g

et it! H

elp!

3

01

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A. Energy decreases.B. Energy increases.C. Energy stays the

same.D. I don’t get it! Help!

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Review Questions What do we call the transfer of energy from place to place? (wave) What do we call the material through which waves travel? (medium) When the medium _______________, a wave is created. (vibrate) How are waves classified? (how they move)

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Review Questions The highest part of a transverse wave is called the

_______________. (crest) The lowest part of a transverse wave is called the

_______________. (trough) What type of wave travels parallel to the direction of the wave

travel? (longitudinal) What type of wave travels perpendicular to the direction of the

wave travel? (transverse)

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Review Questions What type of waves is on top of a pond or lake? (surface) What property of a wave is the maximum distance that particles

of the medium move from resting position? (amplitude) What do we call the distance between two corresponding parts of

a wave? (wavelength) In what units is frequency measured? (hertz)

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Review Questions What is the mathematical relationship between speed of a wave,

frequency and wavelength? (speed = wavelength x frequency) When a wave hits a barrier and bounces back, it is called

_______________. (reflection) When a wave bends because it changes speed as it travels

through different mediums, it is called _______________. (refraction) When a wave bends as it travels around the edge of a barrier it is

called _______________. (diffraction)

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Review Questions The interaction between two waves is called

________________. (interference) Waves combine to make a wave of larger amplitude is called

______________. (constructive interference) Waves combine to make a wave of lower or no amplitude is

called _______________. (destructive interference) What type of wave are two waves that interfere with each other

as they pass each other? (standing)

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Review Questions What occurs when the vibration matches the natural frequency of

the object? (resonance) What are the highest and lowest points called on a standing

wave? (antinodes) What are the points of zero amplitude called on a standing

wave? (nodes) What type of waves does an earthquake produce? (seismic)

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Review Questions Longitudinal seismic waves are called _______________. (primary) Transverse seismic waves are called _______________. (secondary) Which type of seismic wave causes the most damage? (surface) Which seismic wave is the fastest? (primary)

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Review Questions What type of waves requires a medium to pass through? (mechanical) What name is given to the waves produce by underwater

earthquakes? (tsunamis) What machine measures ground movement? (seismograph) What scale is used to measure the magnitude of seismic waves?

(Richter)

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Review Questions What are the areas of a longitudinal wave where the waves are

close together? (compressions) What are the areas of a longitudinal wave where the waves are

far apart? (rarefactions) What is the angle defined by an incoming wave and the

imaginary perpendicular line? (angle of incidence) What is the angle defined by a reflected wave and the imaginary

perpendicular line? (angle of reflection)

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Review Questions What is the relationship between the angle of incidence and the

angle of reflection? (they are equal to each other)