What is a Wave??Wave = Repeating

disturbance/movement that TRANSFERS ENERGY through

MATTER or SPACE

ENERGY can travel in the form of a WAVE

Ex: Ripples on a pond - caused by energy being passed from

molecule to molecule = see this as a WAVE

Waves and Energy

Waves only carry ENERGY as they travel

Waves DO NOT carry MATTER

Ex: Boat on a lake

What Produces Waves??

All waves are produced by VIBRATIONS

Vibration = causes things to move up/down or back/forth

When vibrations stop = energy stops = waves stop

What is a MEDIUM??

Medium = the matter that waves travel through

-Can be: SOLID, LIQUID, or GAS or a combo of the three

Medium for SOUND WAVES =

Medium for OCEAN WAVES =

AIR

WATER

Do all waves travel through a medium??

NO! Radio and light waves can travel

through space

MECHANICAL WAVES

= Waves that can only travel through matter

-2 TYPES:

-1. TRANSVERSE WAVES

-2. COMPRESSIONAL WAVES

TRANSVERSE WAVES

MATTER moves BACK and FORTH at RIGHT ANGLES to the direction that the wave

travels

Ex: Ocean Waves move horizontally towards the

beach

Water within the wave moves up and down (at a right angle

to the wave)

Draw an example and

label with arrows

COMPRESSIONAL WAVES

Matter moves BACK and FORTH in the SAME DIRECTION

the wave travels

AKA: LONGITUDINAL WAVES

Ex: SLINKY

Draw an example and label with arrows

SOUND WAVES

= COMPRESSIONAL WAVES

-Noise pushes nearby air molecules together by their VIBRATIONS (just like in a

slinky)

-The compressions travel through the air to make a

WAVEOn a piece of paper: Explain how sound travels from a

guitar string. What happens when the sound wave

reaches your ear?

WATER WAVES

= TRANSVERSE WAVES (but not completely)

WHAT??Water moves up/down as the wave moves

horizontally but the water also moves a short distance back and forth horizontally

The combo of the up/down and side/side motion causes water to move in CIRCLES = THUS stuff on the surface

absorbs this energy and bobs in a CIRCULAR MOTIONCOOL FACT: Wind causes most ocean

waves. The size of the wave depends on the wind speed, distance over

which the wind blows,and time which the wind blows

SEISMIC WAVES

= Combo of COMPRESSIONAL and TRANSVERSE WAVES

-Travel through Earth and along Earth’s surface

-Carry energy with them

-Objects on Earth’s surface ABSORB some of this energy = MOVE and

SHAKE

-MORE THE CRUST MOVES = MORE ENERGY RELEASED

Turn to pg. 294 in your book.

Read the article.

Questions on Reading pg 294

1.What happens to the surface area of water exposed to the

wind as waves build up?

2. How does this affect the waves?

The surface area INCREASES

The greater the surface area means that there is more contact area

between the air and water, providing an increased area to which energy may

be transferred.

WAVE PARTSTRANSVERSE

WAVESCREST (high point)

TROUGH

(low point)

WAVE PARTSCOMPRESSIONAL WAVES

Compressions

(crowded/dense

regions)

Rarefaction

(spread-apart/less dense regions)

WAVELENGTH

= Distance between one point on a wave to the next point just like it on

the wave

1 Wavelength

1 Wavelength

FREQUENCY AND PERIOD

FREQUENCY: # of wavelengths that pass a fixed point each second

- expressed in Hertz (Hz)

PERIOD: Time it takes one wavelength to pass a fixed

point

- expressed in Seconds (s)

As FREQUENCY INCREASES = PERIOD DECREASES

As FREQUENCY INCREASES = WAVELENGTH DECREASES

WAVE SPEED

Wave Speed = v

Wavelength = lambda

Frequency = f

Speed (m/s) = frequency (Hz) X wavelength (m)

V = f Light waves are _________ than Sound waves

Sound waves travel _______ in solids and liquids than in gasses

Light waves travel _______ in solids and liquids than in gases/space

faster

faster

slower

AMPLITUDE

= Related to the amount of ENERGY a wave carries

GREATER AMPLITUDE = GREATER ENERGY CARRIED

Taller wave = More Amplitude

REFLECTION

= When a wave hits an object and BOUNCES off

of it

-All types of waves can be reflected

Ex: Seeing yourself in a mirror or Echos

Law of Reflection

All Reflected waves obey the following law:

-The Angle of Incidence = The Angle of Reflection

Important TermsINCIDENT BEAM= Light/Sound that 1st strikes an

objectREFLECTED BEAM= Beam bouncing off an object

NORMAL= The line perpendicular to the surface of the object

ANGLE OF INCIDENCE= Angle formed by

Incident Beam and Normal (i)ANGLE OF

REFLECTION= Angle formed by Reflected Beam and Normal (r)

REFRACTION

=Bending of a wave caused by a change in its speed as it moves from one medium to

anotherWaves change speed when they change

mediums

Waves traveling at an angle, change direction

(bend), when they change mediums

Increase change in speed = Increase in Bending of Wave

REFRACTION

Wave enters a medium that slows it down = Bends TOWARD the normal

Wave enters a medium that speeds it up = Bends AWAY

from the normal

DIFFRACTION

When an object causes a wave to change direction

and BEND AROUND ITDiffraction V/S Refraction:

Refraction= wave passes through and bends

Diffraction = wave bends around

Diffraction and Wavelength

1.Obstacle SMALLER than wavelength = wave BENDS

AROUND

2.Obstacle LARGER than wavelength = Less bending

3.Obstacle WAY LARGER than wavelength = NO Diffraction =

Obstacle passes a SHADOW

AM = longer wavelengths than FM. So which gives

better reception in

the mountains?

INTERFERENCE

= When two or more waves overlap and combine to form

a new wave

-New wave exists only while the two waves overlap

-Two types of Combination

1.Constructive Interference

2.Destructive Interference

CONSTRUCTIVE INTERFERENCE

Waves ADD TOGETHER

-Happens when two or more crests or compressions arrive at the same time and

OVERLAP

-Amplitude of new wave = Sum of the old wave amplitudes

-Waves in Constructive Interference = In Phase

What would happen to a the volume of two

sound waves were In Phase?

Draw an Example

DESTRUCTIVE INTERFERENCE

Waves SUBTRACT from each other

-Happens when a crest and a trough meet up or a compression and rarefaction meet

up

-Amplitude of new wave = Difference between the amplitudes of the old waves

-Waves in Destructive Interference = Out of PhaseWhat happens to the

volume if two sound waves are Out of Phase?

Draw an Example

How could this be used to protect

hearing??

STANDING WAVES

= Special type of wave pattern that forms when

waves equal in wavelength and amplitude, traveling in

opposite directions, continue to interfere

-Creates a pattern of crests/troughs that don’t seem to move = “Stands

Still”

-Nodes = places where the two waves cancel = stay in

the same place

RESONANCE

= Process by which an object is made to vibrate by ABSORBING energy at its natural frequency

-All objects have a natural frequency

- If enough energy is absorbed, the object can vibrate so strongly =

breaks!Ex: Tuning Forks

Wine glass (mythbusters)

SOUND WAVES

All sound is created by VIBRATION

Sound Waves are COMPRESSIONAL

Speed is the SLOWEST thru GASES

Speed is the FASTEST thru SOLIDS

How does Temp Affect Speed?

Increase Temperature = Increase Kinetic Energy =

Increase in Collisions = Increase in Speed of Sound

Ex: 0oC = Speed of sound = 331 m/s

20oC = Speed of sound = 343 m/s

LOUDNESS and INTENSITY OF

SOUND

LOUDNESS = Perception of Intensity

Increase the ENERGY in the wave = Increase Loudness

INTENSITY = Amount of energy flowing through an area in a

specific amount of time

Decreases as Distance Increases

DECIBEL SCALE

= dB

-Scale for sound intensity

Ex: 0 dB = faintest sound you can hear

Higher than 120 dB = pain/loss of hearing

PITCH

= How HIGH or LOW a sound seems to be

-Related to the FREQUENCY OF THE WAVE

-High Pitch = High frequency

-Low Pitch = Low frequency

Ex: Whistle = 1000 Hz

Thunder = 50 Hz

DOPPLER EFFECT

= Change in Pitch/frequency

due to moving the wave source

Ex: Race Car Track

Car comes toward you = high pitch

Car goes away from you = low

pitch

ELECTROMAGNETIC WAVES

-Can travel through SPACE (do not need matter)

-Made by: VIBRATING ELECTRIC CHARGES and Magnetic Fields

-TRANSVERSE WAVE (Electric field and Magnetic field are perpendicular to each

other)

Properties of EM Waves

-All objects emit EM waves

-Increase Temp = Decrease in Wavelength

-Energy carried by EM wave = RADIANT ENERGY

- Provides: Warmth, Sight

Properties of EM Waves

-Speed of EM Waves = 300,000 km/s in vacuum of space

-AKA: “Speed of Light”

-”Nature’s Speed Limit” = Nothing is faster!

-Speed changes depending on medium:

-Slowest in Solids

-Fastest in Gases

Properties of EM Waves

Wavelength = Distance from crest to crest

Frequency = # of wavelengths passing a

pt in 1 sec

RELATIONSHIP BETWEEN WAVELENGTH AND FREQUENCY:

F increases = wavelength decreases

EM SPECTRUM

Range of EM wave frequencies

Includes:

-Low-Frequency waves

-Includes the following types:

A. Microwaves = ex: cooking food

B. Radar (Radio Detecting And Ranging) =

ex: Speed, tracking

C. MRI (Magnetic Resonance Imaging) =

ex: Diagnose Illness, pictures of body

EM SPECTRUM

-Thermal energy is produced

-Temperature Increases = Wavelength Decreases

-Ex: Remotes, Computers, Heating food at fast-food restaurants

EM SPECTRUM

-Range of EM waves you can detect with your eyes

-Color = eyes react differently to different wavelengths = you

see color

-Blue = Short Wavelength

-Red = Long Wavelength

-White = All wavelengths of color

EM SPECTRUM

-Higher Frequencies

-Can enter your skin cells = Cancer

-Can be used to KILL BACTERIA

EM SPECTRUM

-Shortest wavelengths and Highest frequencies

-Gamma Rays are shorter than X rays

-X rays = can provide images of organs

-Gamma Rays can kill and damage cells

EM SPECTRUM

EM SPECTRUM

LIGHT WAVES

- To see an object, light must REFLECT off of the object and hit your eye

- Opaque Objects = Absorb and reflect light/NO light passes through (you can’t

see through these objects)

- Translucent Objects = Allow some light to pass through but you can’t see

through it clearly

- Transparent Objects = Transmit almost all light so you can see clearly

through them

REFLECTION OF LIGHT

-Light waves obey the LAW OF REFLECTION

- If all objects reflect light, then why can you see yourself in a

mirror but not in a brick wall??

Brick Walls have BUMPY surfaces which reflect light in all directions whereas a mirror

is very smooth and reflects light mostly back to your eye in

one direction

REFRACTION OF LIGHT

All objects have an INDEX OF REFRACTION =

indicates how much the speed of light is reduced

when it travels through the object

- Higher the Index of Refraction = The more the

speed is slowed down

REFRACTION OF LIGHT

PRISMS- Bend light

-Produce color because the light traveling through the prism bends based

on the wavelength of light

- Sunlight = White Light = Has all wavelengths

- Longer wavelengths are refracted less = Red bends the least

- Rainbows = Water droplets do the same thing as a prism

COLOR

-Color of an object depends on the wavelength the object REFLECTS

-Ex: Red Apple = Reflects RED/Absorbs everything else

-Black = Absorbs all wavelengths

FILTERS

-Color of a filter = color of light it reflects

MIXING COLORS

PIGMENTS = colored material used to change the color of

other substances

- Results from the different wavelengths of light the

pigment reflects

- All colors can be made by mixing 3 color of light

1. Red

2. Blue

3. Green

Primary Colors of

Light