Welcome to 306!   Today is a new marking period – a new start!   DO NOW: Please write three goals you have for yourself in Integrated Science for the second marking period.

Do Now Chapter 11, Waves 11/28/ Take out 11.1,2 and 12.1,2 H/W vocab cards COLLECTED AND GRADED What are the 2 main types of waves

Do Now Chapter 11-12, Waves 11/29/ Take out 11.1 Chapter Review H/W Draw a transverse and longitudinal wave Show direction of particle movement in each wave

Types of Waves  Section  Section 11.1

Waves  A  A disturbance that transmits energy through matter or space

Waves  Most  Most waves move through matter matter called a medium.  Ex.  Ex. Waves traveling through water.

Types of Waves  1. Mechanical Waves a wave that requires a medium through which to travel  Most type of waves Ex.Sound, seismic

Types of Waves  2. Electromagnetic Waves waves caused by the disturbance in electric and magnetic fields and that does not require a medium. (light radiation waves) (light radiation waves)

What do Waves Do?  When  When waves travel through media they are doing work (energy transferred).  Ex.  Ex. Sound traveling in your ear causes vibrates throughout your ear

What do Waves Do?  Ex.  Ex. Shock waves move the earth during an earthquake. Tsunami waves move anything in their path

Shock wave from breaking the sound barrior.

How a Wave Travels  As wave travels in air, the waves spread out in spheres  the sphere will get bigger and bigger as they move farther away

How a Wave Travels  Why is it more damaging to your ears if you are standing next to a speaker rather than a 100 meters away?

How a Wave Travels  Each sphere carries the same amount of energy  But the energy is more spread out of a greater distance.

Speaker Sound waves

Vibrations and Waves  Most  Most waves are caused by a vibrating object, which will then cause other objects to vibrate  Vibrations  Vibrations will transfer energy from PE to KE.

Vibrations and Waves  simple  simple harmonic motion--vibration would continue forever  Damped  Damped harmonic motion transfers the energy and the vibration will fade out.  Ex.  Ex. Shock absorbers on cars and bikes.

Wave Vibration Types  1.  1. Transverse Waves -a wave that causes the particles of the medium to vibrate perpendicular to the direction of the wave.  “The  “The Wave” at a stadium is a good illustration.  Ex.  Ex. Light waves

Wave Vibration Types  2.  2. Longitudinal Waves -a wave that causes the particles of the medium to vibrate parallel to the direction of the wave.  they  they expand and compress.  Ex.  Ex. Sound waves

Wave Vibration Types  3.  3. Surface Waves -waves that are both transverse or longitudinal. -Circular motion -ex. Ocean waves

Wave Types  Mechanical waves: -can be transverse, longitudinal, or surface waves  Electromagnetic (light): -waves will only be transverse.

DO NOW   EAWV SCCARHATRISTECI   UNSCRAMBLE THE TERMS ABOVE TO FIND OUT WHAT WE ARE LEARNING ABOUT TODAY!   Be Ready to hear an important message!

Characteristics of Waves 11.2

Wave Properties  all transverse waves have similar shapes, no matter the size of the wave.  The shape is called a sine curve or sine wave.

Sine Wave

Wave Parts  Crest Highest point of a transverse wave  Trough lowest point of a transverse wave

Wave Parts  Amplitude -The vertical distance that particles vibrate from their normal position when a wave passes  measures the intensity of wave. -ex.Loudness, brightness

Wave Parts  Wavelength -The distance between any two successive identical parts of a wave  Represented by the symbol lambda ( )  Measured in a degree of meters

Wave Diagram Wave Diagram trough Wavelength Crest Amplitude Wavelength

Wave Properties  1. Wavelength -measures the size of the wave

Wave Properties  2. Amplitude -measures the intensity (strength) of the wave

Wave Properties  3. Frequency -the number of full wavelengths that pass a point in a particular period of time (rate) -Represented by the symbol (ƒ) -Measured in hertz (Hz) = beat/sec -Your radio dials are in megahertz

Wave Properties  4. Period (time) -The time required for one full wavelength to pass a certain point -Represented by the symbol (T) -Measured in seconds

Wavelength High Low High

Frequency, wavelength, and Period  Wavelength and period will increase when frequency decreases.  λ ↓, T, ↓, then f ↑

Frequency and Period  You can calculate frequency and period from each other  T=1/f or f=1/T

Frequency and Sound  We hear sounds from the range 20 Hz to 20,000 Hz  determines the pitch

Pitch and Loudness Pitch and Loudness

Breaking Glass Breaking Glass

Frequency and Light  We see light from the range 4x10 14 Hz red to 8x10 14 Hz violet  Frequency determines the energy and color  Red is the easiest to see, violet is the hottest (most energetic)

Wave Properties 5. Wave Speed -the speed at which a wave passes through a medium. -Waves travel at different speeds in different media phases (s, l, g).

Mechanical Wave Speed  These waves travel fastest in solids and the slowest in gases  Why? (essay question)

sonic boom

Light Wave Speed  all electromagnetic waves travel at the same speed in empty space. (3 x 10 8 m/s)  Light waves slow down as they pass through media.

Vocab Solutions   Amplitude – greatest distance particles in a medium move from their normal position when a wave passes   Wavelength – distance between any two successive identical parts of a wave   Crest- highest point of a transverse wave   Trough- Lowest point of a transverse wave.

Wave Speed Equations  Speed=wavelength/period  v= /T Can also use:  Speed=frequency x wavelength  v = f x  v = f x

Examples  A piano string vibrates with a frequency of 264 Hz. If the waves have a wavelength of 1.3 m, what is the speed of sound in air?

Examples  v= f  speed= (1.30 m) (264 Hz)  speed = 343 m/s

Examples A string with a wavelength of 1.30 m and a period of s is played. What is the speed of the wave?

Examples  V = /T  speed=1.30 m/ s  speed = 343 m/s

Doppler Effect  an observed change in the frequency of a wave when the source or observer is moving  Object approaches with high frequency but low wavelength, but as it passes the frequency lowers as the wavelength increases

Doppler effect

Standing Waves  wave that appears not to move along the medium.  two regions

Standing Waves  Regions of no vibrations (nodes)  Regions of maximum vibration (antinodes)

Wave Interactions 11.3

1. Reflection  The bouncing back of a wave as it meets a surface or boundary

2. Diffraction  When waves pass through an opening or by an edge the bend around the edge or expand as they pass through the opening.

3. Refraction  The bending of waves as they pass from one medium to another

Refraction  Air to water is an example  Ex. Spoon seeming to bend when placed in water

4. Interference  The combination of two or more waves that exist in the same place at the same time.  Once waves pass, they return to original shape

Interference  Two types: 1. Constructive 2. destructive

Constructive Interference  The crests of wave line up to combine their amplitudes making the wave larger.  Wave becomes bigger

Constructive Interference  The new wave is bigger than the original when waves combine

Destructive Interference  When crest of one wave meets the trough of another wave  Forms a smaller wave than the original

Interference of Light Waves  When light waves interfere with each other, colorful displays are produced.  Soap bubbles

Interference of Sound Waves  When two waves with different frequencies interfere with each other, beats are produced