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Types of Waves
Section
11.1
Waves
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 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
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
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
harmonic motion-vibration would continue forever
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 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 Vibration Types
2.
Longitudinal Waves
-a wave that causes the particles of
the medium to vibrate parallel to
the direction of the wave.
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.
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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
Wavelength
Amplitude
Crest
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) = 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/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
Frequency and Light
We
see light from the range
4x1014 Hz red to 8x1014 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
8
empty space. (3 x 10 m/s)
Light waves slow down as
they pass through media.
Wave Speed Equations
Speed=wavelength/period
v=/T
Can also use:
Speed=frequency x wavelength
v
=fx
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 0.00379 s is
played. What is the
speed of the wave?
Examples
= /T
speed=1.30 m/0.00379 s
speed = 343 m/s
V
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