Wave
Properties
Interference
Wave Properties
There are 6 main properties, or interactions, of
waves that occur when a wave comes in contact
with another wave , or a boundary.
The 6 Interactions of waves are






Interference
Diffraction
Reflection
Refraction
Absorption
Polarization
Interference
When two or more waves
combine together.
Superposition principle
 There
are typically many waves in the same
system at the same time.
 When more than one wave is present, the
total oscillation of any point is the sum of the
oscillations from each individual wave.
 The sound waves and light waves you
experience are the superposition (adding up)
of thousands of waves with different
frequencies and amplitudes.
 Your eyes, ears, and brain separate the
waves in order to recognize individual sounds
and colors.
Constructive Interference
Constructive
interference occurs when waves
add up to create a larger amplitude wave.
These
waves are in-phase with each other.
Constructive Interference
When two waves combine to make a larger wave.
(crest & crest) or (trough & trough)
Destructive Interference
 Destructive
interference occurs when waves
add up to make a smaller amplitude wave.
 These
other.
waves are out-of-phase with each
Destructive Interference
 Two
or more waves combine to produce a smaller
wave or destroy the wave completely.
(crest & trough)
Check for Understanding!
1.
2.
Results of Interference of Waves
 One
of the consequences of wave interference is a
phenomenon called resonance.
 Resonance
is the reinforcing of an object’s natural
frequency so that the amplitude increases very
quickly.
 Can
you think of something that you have seen or
heard that you believe to be caused by
resonance?
Standing Waves

A wave that is confined
between boundaries is
called a standing wave.

With all waves, resonance
and natural frequency
are dependent on
reflections from
boundaries of the system
containing the wave.

Resonance occurs when
the reflected pulses add
together to form a large
amplitude pulse.
Resonance
Resonance
can also occur when one
object vibrates another without
touching
A
sound wave vibrates a snare drum
 A singer hits a note that shatters a glass
 A struck tuning fork causes another
tuning fork of the same frequency to
vibrate
 The strings of a guitar vibrate from a
sound across the room
Resonance
Natural Frequency and Resonance
The
natural frequency is sometimes called the
resonant frequency because the frequencies are the
same when the large amplitudes begin to occur.
Resonance
Real World Examples:
Chinook Helicopter Ground Resonance Test
The Tacoma-Narrows Bridge is an example
of driven oscillations that result in large
amplitude oscillations.
Today’s Assignment
 For
your grade today, you and your elbow partner
need to find a picture, newspaper article, news
report or video of an example of Resonance that I
have not already given you.
I
will give you 10 minutes to research on your
phones or an iPad.
 Raise
your hand when you are ready to show me
and explain your example.
I
will come by every group to see what you have
done for your grade today!