Download Unit 3 Lesson 2

Unit 3 Lesson 2 Properties of Waves
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Unit 3 Lesson 2 Properties of Waves
Florida Benchmarks
• SC.7.P.10.3 Recognize that light waves, sound
waves, and other waves move at different speeds
in different materials.
• MA.6.A.3.6 Construct and analyze tables, graphs,
and equations to describe linear functions and
other simple relations using both common
language and algebraic notation.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
Florida Benchmarks
• LA.6.4.2.2 The student will record information
(e.g., observations, notes, lists, charts, legends)
related to a topic, including visual aids to organize
and record information and include a list of
sources used.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
Amp It UP!
How can we describe a wave?
• Waves can be described by basic properties.
• In a transverse wave, there are special terms for
the maximum displacement of particles in the
wave.
• The highest points are crests; the lowest points
are troughs.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
How can we describe a wave?
• A wave’s amplitude is a measure of how far
particles in the medium move away from their
normal rest position.
• Wavelength is the distance over which the
wave’s shape repeats.
• Wavelength is the distance from any point on a
wave to an identical point later on the wave.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
How can we describe a wave?
• What is the wavelength of this wave? What is the
wave’s amplitude?
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
How can we describe a wave?
• Another property is wave period, the time
required for one wavelength to pass a given point.
• Frequency is also a way to express how far apart
waves are in time. It is the number of crests that
pass a point in a certain amount of time.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
How can we describe a wave?
• Frequency is measured in hertz (Hz). One hertz
equals one wavelength per second.
• Frequency is the inverse of period.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
Amp It Down
What affects the energy of a wave?
• Some waves carry more energy than others.
• Friction has a dampening effect on waves,
meaning it causes them to lose energy.
• The amount of energy a mechanical wave carries
determines its amplitude.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
What affects the energy of a wave?
• The amplitude of a sound wave corresponds to its
volume.
• In an electromagnetic (EM) wave, energy depends
on frequency as well as amplitude.
• High-frequency waves carry more energy than
low-frequency waves.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
What affects the energy of a wave?
• Many waves spread out in circles or spheres,
called wave fronts.
• As the circle expands, there is less energy
available on the wavefront.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
A Happy Medium
What determines the speed of a wave?
• Wave speed, or the speed at which waves travel,
depends on the properties of the medium.
• Waves tend to travel slower in a denser medium.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
A Happy Medium
What determines the speed of a wave?
• In gases, wave speed is higher in higher
temperatures.
• All electromagnetic waves travel at the same
speed in empty space, but they travel more slowly
through a denser medium.
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
What determines the speed of a wave?
• Wave speed can be calculated from frequency and
wavelength.
• Speed is a distance divided by time.
• Speed is also Wavelength times frequency
Copyright © Houghton Mifflin Harcourt Publishing Company
Unit 3 Lesson 2 Properties of Waves
What determines the speed of a wave?
• Wave speed is a wavelength divided by wave
period.
• This relationship can be combined with the
relationship between wavelength and frequency.
• The wavelength is equal to the wave speed
divided by its frequency.
Copyright © Houghton Mifflin Harcourt Publishing Company