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What are waves?
https://www.youtube.com/watch?v=j-zczJXSxnw
https://www.youtube.com/watch?v=ynqzeIYA7Iw
What are waves?
• Waves are rhythmic movements
that carry energy through space
or matter.
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Types of Waves
•Sound waves
•Light waves
•Electromagnetic waves
•Ocean waves
•Radiation
•Seismic waves
•Heat waves
•Transverse waves
•Longitudinal waves
Waves are classified by what they are travel through...
SO……
There are two main types of
waves
•Mechanical waves
•Electromagnetic waves
What are some types of waves?
• Waves such as water waves that require a
medium are called mechanical waves.
Copyright © Houghton Mifflin Harcourt Publishing Company
Mechanical Waves
• Some mechanical waves can travel through
more than one medium.
• For example, sound waves can move through
air, water, and a solid wall.
• Mechanical waves can’t travel without a
medium.
Copyright © Houghton Mifflin Harcourt Publishing Company
Electromagnetic Waves
• Electromagnetic (EM) waves are not
disturbances in a physical medium. They are
vibrations of electric and magnetic fields.
• Sunlight is an example of EM waves. Other
examples include radio waves, microwaves, and
X-rays.
• In empty space, all EM waves travel at the same
speed, called the speed of light.
Copyright © Houghton Mifflin Harcourt Publishing Company
A sound wave is different than a light wave in
that a sound wave is
a. produced by an oscillating object and a light
wave is not.
b. not capable of traveling through a vacuum.
c. not capable of diffracting and a light wave is.
d. capable of existing with a variety of
frequencies and a light wave has a single
frequency.
2 main ways to transfer energy
• Waves can be classified by comparing
the direction that they cause particles
in the medium to move with the
direction in which the wave moves.
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How do waves transfer energy?
• Energy can be transferred from one object to
another using compressions and rarefactions. This
causes energy to travel in a longitudinal wave.
•
•
•
•
Compressions – the energy is close together
Rarefactions-the energy is separated
Sound waves
travel parallel
Copyright © Houghton Mifflin Harcourt Publishing Company
How do waves transfer energy?
• Energy can be transferred from one object to
another using up and down motions. This causes
energy to travel as a transverse wave.
• In a transverse wave, particles move
perpendicularly to the direction the wave travels.
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Characteristics of waves
Crests and Troughs
• The points where a wave is highest are called
crests. The points where a wave is lowest are
called troughs.
Copyright © Houghton Mifflin Harcourt Publishing Company
Amplitude:
•
•
•
•
Distance between “rest & crest” or “rest &
trough”
Gives indication of “power”
or “strength” of wave
Does not affect
velocity of wave
Determines loudness (sound) or brightness
(EM wave)
Wavelength:
Distance between any two
repeating points on a wave
crest-crest,
trough-trough,
expansion-expansion,
compression-compression
Determines what colors
we see; what notes we hear
(pitch)
Shorter wavelengths have more
cycles per minute because
they aren’t as long
Velocity
•The rate at which energy
travels
•Depends on the medium
• Mechanical waves travel
faster through dense
mediums
• EM Waves are faster
through less dense
mediums
• Frequency x wavelength
Frequency:
•
number of wavelengths that
pass any point per second
•
measured in
wavelengths/second or
cycles/second
Hertz (Hz) = number of
wavelengths in 1 second
•
Frequency is related to
velocity: v = ƒ 
The distance between two
corresponding parts of a wave
is the wave’s
a. amplitude.
b. wavelength.
c. frequency.
d. speed.
What is the frequency of a wave that has
a speed of 0.4 m/s and a wavelength of
0.020 meter?
a. 10 hertz.
b. 20 hertz.
c. 0.008 hertz.
d. 0.5 hertz.
The speed of a wave is its
wavelength multiplied by its
a. amplitude.
b. vibration.
c. frequency.
d. reflection.
What is the amplitude of this wave?
A wave travels through a medium because
a. the
medium’s particles are carried along
with the wave.
b the wave’s energy passes from particle
to particle.
c. the medium transfers electromagnetic
energy.
d the wave increases the potential energy
of its medium.
.
.
Why do you see lightning from a distant storm
before you hear thunder?
a The thunder is produced after the
lightning.
b Your eyes react faster than your ears.
c Light travels faster than sound.
d Sound travels faster than light.
The distance between two corresponding
parts of a wave is the wave’s
a. amplitude.
b. wavelength.
c. frequency.
d. speed.
If the distance from point A to point B
in the diagram is 60 cm, then the
wavelength is ____.