unit 3 lesson 2 properties of waves copyright © houghton mifflin harcourt publishing company

Unit 3 Lesson 2 Properties of Waves

Copyright © Houghton Mifflin Harcourt Publishing Company


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.


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.

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.



• 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.






• What is the wavelength of this wave? What is the wave’s amplitude?


• 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.




• Frequency is measured in hertz (Hz). One hertz equals one wavelength per second.

• Frequency is the inverse of period.



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.



• 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.




• Many waves spread out in circles or spheres, called wave fronts.

• As the circle expands, there is less energy available on the wavefront.



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.


A Happy Medium



• 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.



• Wave speed can be calculated from frequency and wavelength.

• Speed is a distance divided by time.




• 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.



unit 3 lesson 2 properties of waves copyright © houghton mifflin harcourt publishing company

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