Download Getting to Know: Characteristics and Properties of Waves

Getting to Know: Characteristics and Properties
of Waves
At many beaches, you can see ocean waves rolling in, one after another. Some are tall, covering the entire beach when they hit. Some just lap gently at the water’s edge. Sometimes the waves roll in quickly, one right after the other. Sometimes minutes may pass between waves.
You can describe ocean waves by their characteristics such as height or amplitude; distance from one wave to the next, called the wavelength; and the rate, or frequency, at which the waves pass the breaking point. Ocean waves are a type of mechanical wave, in which energy moves
through a medium, in this case water. Many forms of energy travel as waves. Although different types of waves have some different properties, all waves share the same basic characteristics of height, wavelength, and frequency.
Surfers learn to read the characteristics
of ocean waves such as amplitude,
wavelength, and frequency to stay safe
and get the best rides.
What are waves?
Waves are regular patterns of change that carry energy. A wave is started by a pulse of energy
and then continued as energy moves away from the source. Some waves travel through
matter—just as ocean waves travel through water—but it is important to understand that
waves do not carry matter from one place to another, they only carry energy.
Misconception 1: Ocean waves move water from one area to another.
As you watch waves break on the beach, it may appear as if they are carrying water from
far out at sea. However, this is a bit of an optical illusion. The water you see breaking on
the shore is the same water washing up and back over and over again throughout the
day. Imagine floating on a raft out at sea, bobbing up and down on the waves. As the
waves pass by, you travel in an up-and-down motion. You are not carried forward with a
single wave.
Concept: Characteristics and Properties of Waves
Getting to Know
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Why are some ocean waves so big?
The amplitude of a wave relates to the amount of energy the wave carries. Waves with greater
amplitude carry more energy than waves with lower amplitude. In most cases, large ocean
waves get started when strong winds push against the water. The depth of the water and the
shape of the ocean floor also play a role in wave size and shape. The energy in an ocean wave
is carried below the surface the same distance that it is carried above the surface. If the wave
hits the ocean floor, some energy is transferred to the sand and rocks instead of being carried
back up toward the surface. When this happens, only smaller waves develop.
Other important characteristics of waves are
wavelength and frequency. Wavelength is measured
as either the distance from the top, or crest, of one
wave to the crest of the adjacent wave or from the
bottom, or trough, of one wave to the trough of
the adjacent wave. Frequency is measured as the
number of waves that pass a certain point in a given
amount of time.
What are some examples of waves?
Two types of waves are known as mechanical
waves and electromagnetic waves. Mechanical
waves can only propagate through matter
When you sing and play music, you create
and include examples such as sound waves,
sound waves that carry energy through
the air.
earthquake or seismic waves, and ocean waves.
Electromagnetic waves can carry electromagnetic
energy through empty space as well as matter. Light, microwaves, and X-rays are examples of electromagnetic waves, which do not require matter to travel. That is how light and heat energy from the Sun can travel through space to reach Earth’s surface.
Misconception 2: Sound waves don’t need to travel through matter because they
go through the empty space around us.
Remember, the air that surrounds us is not empty space, but matter composed of
molecules in a gaseous state. Sound waves move through air by pressing air molecules
together in some places and spreading them apart in others. This type of wave is called
a compression wave, which moves molecules back and forth in a straight line rather
than up and down like an ocean wave. However, compression waves are similar to
up-and-down waves, or transverse waves, in many ways. They carry energy, not matter,
and have the properties of amplitude, wavelength, and frequency.
Now that you know a little more about waves, let’s get started with our lesson—there are lots
of details still to learn!
Concept: Characteristics and Properties of Waves
Getting to Know
www.discoveryeducation.com
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© Discovery Education. All rights reserved.
Discovery Education is a subsidiary
of Discovery Communications, LLC.