Describe a Wave
Chapter 14Waves &
Energy Transfer
Wave•A rhythmic
disturbance that carries energy through matter
Wave Pulse•A single bump or
disturbance that travels through a
medium
Continuous Wave•The rhythmic disturbance that travels through a
medium
Types of Waves
Transverse Wave•A wave that vibrates perpendicular to the
wave motion
Transverse Wave•A good
representation would be a sine wave
Longitudinal Wave
•A wave that vibrates parallel to the wave motion
Longitudinal Wave
•A good representation
would be a slinky
Surface Wave•A wave that travels
on the border of two mediums
Surface Wave•Have both transverse & longitudinal
characteristics
Surface Wave•Good examples are
swells or surface water waves
Mechanical Waves
Waves that require a medium
Electromagnetic Waves
Waves that do not require a medium
Ray•A vector
representing the wave & its direction
Measuring Waves
Wave Speed•How fast a wave is
moving through a medium
Wave Speed
v = d/t
Wave Speed•Measured in
m/s
Wave Speed•All waves move at a constant speed in
a given medium
-1
-0.5
0
0.5
1
0 2 4 6 8 10
Crest
Trough
Amplitude
Wavelength ()
Wavelength ()•The distance between corresponding points
in a wave
Wavelength ()•Measured in m or
some form of m
Displacement•The perpendicular
distance a wave vibrates from zero
Amplitude•The maximum
displacement a wave vibrates from zero
Frequency (f)()•The number of
waves per unit time
Frequency•Measured in hertz
(Hz) •(cycles/s or waves/s)
Period (T)•The time measured in (s) for one wave to pass or the time for
one cycle
Frequency Period Formula
T = 1/f
Wave Velocity Formula
v = f
You are 525 m from a clock tower. You hear a
clock’s chime at 436 Hz in 1.50 s. Calculate: v, T, & of the sound
wave
You shout towards a wall 0.685 km away producing a 75 cm wave. You hear the
echo in 4.00 s. Calculate: v, T, & f
Surface Waves•At wave boundaries
exhibiting both transverse &
longitudinal properties
Wave Speed•All waves move at a constant speed in
a given medium
Waves passing from one medium
to another
Incident Wave•The waves that
strikes a boundary of a given medium
Reflected Wave•The waves that bounces off the
boundary & returns
Transmitted Wave
•The waves that passes from one
medium to another
Wave BehaviorWhen waves pass from one medium to another
they are both transmitted & reflected
Radio waves travel at 3.00 x 108 m/s. Calculate the
wavelength of your favorite radio station.
Wave BehaviorWaves transmitted from
one medium to another stay in phase or do not
invert
Wave BehaviorThe amplitude change in
both transmitted waves & reflected waves is
dependent on % transmitted
Wave Behavior
When colliding with a more dense medium, reflected waves invert
Wave Behavior
When colliding with a less dense medium, reflected waves stay
erect or in phase
Wave Behavior
When waves pass from one medium to another
of , the frequency remains constant
Wave BehaviorWhen waves pass from one medium to another of different density, the
speed changes
Wave Behavior
The speed of longitudinal waves is
proportional to the density of the medium
Wave Behavior
The speed of transverse waves is inversely proportioned to the
density of the medium
Wave Behavior
v = f, thus is inversely
proportioned to f
A tsunami is formed 1800 km away
producing a 60 ft tidal wave that strikes shore 3.0 hr later. Calculate:
vwave in m/s
Interference
The effect of two or more waves passing through a medium
simultaneously
Principle of Superposition
At the point where 2 or more waves meet, the
total displacement is the sum of all the individual
displacements
Constructive Interference
When the interference of waves is crest to
crest
Constructive Interference
Will result in waves of larger amplitude
Destructive Interference
When the interference of waves is crest to
trough
Destructive Interference
Will result in waves of smaller amplitude
NodeA point in a medium that
goes through no displacement when waves pass through
each other
NodeA point in a medium that
goes through no displacement when waves pass through
each other
AntinodeA point in a medium that goes through maximum
displacement when waves pass through
each other
Standing WaveThe result of identical
waves moving in opposite directions
Standing Wave
A guitar string is a good example
Waves in Two Dimensions
Reflected Wave
When a wave bounces off a wave
boundary
Law of ReflectionWhen a wave strikes a
boundary at an angle other than normal, the reflected angle equal the angle of incident
Law of Reflection
reflection = incident
RefractionWhen a wave strikes a
boundary at an angle other than normal, the
angle of the transmitted ray is changed
RefractionThe bending of waves
passing from one medium to another due
to speed change
Less DenseMedium
More Dense
MediumNormal
Diffraction
The bending of waves around a barrier
DiffractionWhen a wave passes
through a small opening, the wave will exit in a semi-circular
pattern
Three waves (1.0 m, 0.60 m, & 0.50 m) pass simultaneously through
a medium. Calculate maximum & minimum
displacement:
Red light with a wavelength of 600.0 nm travels through space at
3.00 x 108 m/s. Calculate its:
frequency & period
A 60.0 Hz note from a base guitar travels
through a hot room at 360 m/s. Calculate its:wavelength & period
A series of 6.0 ft waves move towards an island.
Determine the side of the island where the
waves will be the largest. Front of back
Three waves (2.0 m,1.5 m, & 1.2 m) pass
simultaneously through a medium. Calculate
maximum & minimum displacement:
Blue light with a wavelength of 450 nm travels through space at
3.00 x 108 m/s. Calculate its:
frequency & period
An 85 Hz note from a bass guitar travels
through a room at 340 m/s. Calculate its:
wavelength & period
Island Phenomenon
Answer the questions on page 268 & 269, and
work problems a on page 269.