Types of Waves Section Section 11.1
Waves A A disturbance that transmits energy through matter or space
Waves Most waves move through matter called a medium. 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)
What do Waves Do? When When waves travel through media they are doing work (energy transferred). Ex. Sound traveling in your ear causes vibrates throughout your ear
What do Waves Do? Ex. Shock waves move the earth during an earthquake. Ex. 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 Each sphere carries the same amount of energy But the energy is more spread out
Speaker Sound waves
Vibrations and Waves Most waves are caused by a vibrating object, which will then cause other objects to vibrate 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. Shock absorbers on cars and bikes.
Wave Vibration Types 1. Transverse Waves -a a wave that causes the particles of the medium to vibrate perpendicular to the direction of the wave. The Wave at a stadium is a good illustration. Ex. Light waves
wave commerical
Wave Vibration Types 2. Longitudinal Waves -a a wave that causes the particles of the medium to vibrate parallel to the direction of the wave. they they expand and compress. Ex. Sound waves
Wave Vibration Types 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.
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 CrestCrest Highest point of a transverse wave TroughTrough lowest point of a transverse wave
Amplitude Wave Parts -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 (λ)( Measured in a degree of meters
Wave Diagram Wavelength Crest Amplitude Wavelength trough
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) or 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
Low Low Wavelength High 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/ 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
Breaking Glass
Frequency and Light We see light from the range 4x10 14 Hz red to 8x10 14 Hz violet Frequency determines the energy Red Red is the easiest to see, violet is the hottest
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 These waves travel fastest in solids and the slowest in gases Why? 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.
Wave Speed Equations Speed=wavelength/period v= v=λ/t Can also use: Speed=frequency x wavelength v v = f x λ
Examples A 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= λ f speed= speed= (1.30 m) (264 Hz) speed speed = 343 m/s
Examples A string with a wavelength of 1.30 m and a period of 0.00379 s is played. What is the speed of the wave?
V V = λ/t Examples speed=1.30 m/0.00379 s speed speed = 343 m/s
Doppler Effect an observed change in the frequency of a wave when the source or observer is moving Object Object approaches with high frequency but low wavelength, but as it passes the frequency lowers as the wavelength increases
Doppler effect
Wave Interactions 11.3
1. Reflection The bouncing back of a wave as it meets a surface or boundary
2. Diffraction When 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 Once waves pass, they return to original shape
Two types: 1. Constructive 2. destructive Interference
Constructive Interference The crests of wave line up to combine their amplitudes making the wave larger. Wave Wave becomes bigger
Constructive Interference The new wave is bigger than the original when waves combine
Destructive Interference When When crest of one wave meets the trough of another wave Forms Forms a smaller wave than the original
Interference of Light Waves When When light waves interfere with each other, colorful displays are produced. Soap Soap bubbles
Interference of Sound Waves When When two waves with different frequencies interfere with each other, beats are produced
Standing Waves wave wave that appears not to move along the medium. two regions
Standing Waves Regions Regions of no vibrations (nodes) Regions Regions of maximum vibration (antinodes)