Unit 5 Lesson 2 Properties of Waves Copyright © Houghton Mifflin Harcourt Publishing Company 1

How do people use light waves to see during the day? Unit 5 Lesson 2 Properties of Waves Bell Ringer #2 -Copy the question and answer it to the best of your ability. How do people use light waves to see during the day? Copyright © Houghton Mifflin Harcourt Publishing Company 2

Lesson 2: Vocabulary Amplitude Wavelength Wave period Frequency Hertz Unit 5 Lesson 2 Properties of Waves Lesson 2: Vocabulary Amplitude Wavelength Wave period Frequency Hertz Wavefront Wave speed Copyright © Houghton Mifflin Harcourt Publishing Company 3

Lesson 2: Properties of Waves Unit 5 Lesson 2 Properties of Waves Lesson 2: Properties of Waves Essential Question: How can we describe a wave? Copyright © Houghton Mifflin Harcourt Publishing Company 4

Amp It UP! How can we describe a wave? Unit 5 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 5

How can we describe a wave? Unit 5 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 6

How can we describe a wave? Unit 5 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 7

How can we describe a wave? Unit 5 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 8

Amp It Down What affects the energy of a wave? Unit 5 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 9

What affects the energy of a wave? Unit 5 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 10

What affects the energy of a wave? Unit 5 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 11

A Happy Medium What determines the speed of a wave? Unit 5 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 12

A Happy Medium What determines the speed of a wave? Unit 5 Lesson 2 Properties of Waves A Happy Medium What determines the speed of a wave? In gases, wave speed is higher at 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 13

What determines the speed of a wave? Unit 5 Lesson 2 Properties of Waves What determines the speed of a wave? Wave speed can be calculated from frequency and wavelength. Speed is distance divided by time. Copyright © Houghton Mifflin Harcourt Publishing Company 14

Write a 2-3 sentence summary on what you learned in this set of notes. Unit 5 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. Wavelength is equal to the wave speed divided by its frequency. Write a 2-3 sentence summary on what you learned in this set of notes. Copyright © Houghton Mifflin Harcourt Publishing Company 15