Characteristics of Waves
Chapter 9
S8P4a. Identify the characteristics of
electromagnetic and mechanical waves.
S8P4d. Describe how the behavior
of waves is affected by medium
(such as air, water, solids.)
S8P4f. Diagram the parts of the wave
The Nature of Waves
1) A wave is any disturbance that
transmits energy through matter or
space
Examples: water waves in the ocean
microwaves
light waves
radio waves
sound waves
2) Waves carry energy away from
their source, but they DO NOT
carry material
3) The substance the wave passes
through is called a medium.
Sound waves and ocean waves
require a medium – they are called
mechanical waves.
4) Electromagnetic waves can
transfer energy without
traveling through a medium.
Examples?
light,
microwaves,
TV and radio signals,
X-rays
5) Two types of wave
motion:
a) transverse
b) longitudinal
6) In longitudinal waves the
particles of the medium
vibrate back and forth in
the path of the wave –
7) Transverse waves move up and
down – particles move perpendicular
to the path of the wave
Reminder:
All electromagnetic waves are
transverse, but not all transverse
waves are electromagnetic
Ex: light – electromagnetic + transverse
Ocean waves: mechanical and transverse
BUT: all longitudinal waves ARE mechanical
Summary point 1:
Turn to your neighbor and explain:
What do electromagnetic and
mechanical waves have in common.
What makes mechanical waves
different from electromagnetic.
Write the answers to both questions
in your notes.
Properties of Waves
1) The amplitude of a
wave is its height above
the rest position.
A larger amplitude means more energy
2) The wavelength is the
distance between two
crests or two
compressions
wavelength
3) Frequency: the number of
waves produced in a given
amount of time; greater
frequency means more energy
4) Wave speed –
the speed of the wave
Wave speed= wavelength X frequency
1) Draw a transverse wave on your
paper – label amplitude and
wavelength, crest and trough
2) Draw 2 transverse waves on your
paper. Make wave A have a high
frequency and wave B have a low
frequency. Label each.
Wave Interactions
Or, What happens when waves
hit stuff?
1) Reflection: waves
bounce back after
hitting something
2) Refraction occurs when waves
bend when they pass from one
substance to another.
3) Diffraction occurs when waves
bend as they pass through an
opening or around a corner.
4) Interference occurs
when two or more waves
overlap.
This
Constructive
interference
occurs when
overlapping
waves get bigger.
4b) Destructive interference
occurs when overlapping waves get
smaller.
http://phet.color
ado.edu/en/simul
ation/waveinterference
This
5) Standing waves result from
interference that creates a
stationary pattern of waves.
http://web.ncf.ca/ch865/frenchdescr/StandingWaveString.html
6) Resonance occurs when one object
causes another to vibrate without
touching it
Tacoma Narrows Bridge
Breaking a wine glass
using resonance