Unit 3 Lesson 1 Waves Copyright © Houghton Mifflin Harcourt Publishing Company 1

Unit 3 Lesson 1 Waves Florida Benchmarks SC.7.N.1.1 Define a problem from the seventh grade curriculum, use appropriate reference materials to support scientific understanding, plan and carry out scientific investigations of various types, such as systematic observations or experiments, identify variables, collect and organize data, interpret data in charts, tables, and graphics, analyze information, make predictions, and defend conclusions. Copyright © Houghton Mifflin Harcourt Publishing Company 2

Unit 3 Lesson 1 Waves Florida Benchmarks SC.7.P.10.3 Recognize that light waves, sound waves, and other waves move at different speeds in different materials. Copyright © Houghton Mifflin Harcourt Publishing Company 3

Riding the Wave What are waves? Unit 3 Lesson 1 Waves Riding the Wave What are waves? Water waves are just one of many kinds of waves. Sound and light are also waves. Waves are caused by vibrations of a medium. A medium is the material through which a wave can travel. Waves transfer energy from one place to another. Copyright © Houghton Mifflin Harcourt Publishing Company 4

Unit 3 Lesson 1 Waves What are waves? The points where a wave is highest are called crests. The points where a wave is lowest are called troughs. Copyright © Houghton Mifflin Harcourt Publishing Company 5

Unit 3 Lesson 1 Waves What are waves? Some waves, such as ocean waves, transfer energy through a medium. Some waves, such as light waves, can transfer energy without a medium. Copyright © Houghton Mifflin Harcourt Publishing Company 6

Different Ways to Transfer Energy Unit 3 Lesson 1 Waves Different Ways to Transfer Energy How do waves transfer energy? Not all waves transfer energy the same way. Waves can be classified by comparing the direction that they cause particles in the medium to move with the direction in which the wave moves. Copyright © Houghton Mifflin Harcourt Publishing Company 7

How do waves transfer energy? Unit 3 Lesson 1 Waves How do waves transfer energy? Energy can be transferred from one object to another using compressions and rarefactions. This causes energy to travel in a longitudinal wave. Compressions – the energy is close together Rarefactions the energy is separated. Sound waves are longitudinal waves. Longitudinal waves travel parallel Copyright © Houghton Mifflin Harcourt Publishing Company 8

How do waves transfer energy? Unit 3 Lesson 1 Waves How do waves transfer energy? Energy can be transferred from one object to another using up and down motions. This causes energy to travel as a transverse wave. In a transverse wave, particles move perpendicularly to the direction the wave travels. Copyright © Houghton Mifflin Harcourt Publishing Company 9

Making Waves What are some types of waves? Unit 3 Lesson 1 Waves Making Waves What are some types of waves? Waves can also be classified by what they are traveling through. Waves such as water waves that require a medium are called mechanical waves. Copyright © Houghton Mifflin Harcourt Publishing Company 10

What are some types of waves? Unit 3 Lesson 1 Waves What are some types of waves? Some mechanical waves can travel through more than one medium. For example, sound waves can move through air, water, and a solid wall. Mechanical waves can’t travel without a medium. Copyright © Houghton Mifflin Harcourt Publishing Company 11

What are some types of waves? Unit 3 Lesson 1 Waves What are some types of waves? Electromagnetic (EM) waves are not disturbances in a physical medium. They are vibrations of electric and magnetic fields. Sunlight is an example of EM waves. Other examples include radio waves, microwaves, and X-rays. In empty space, all EM waves travel at the same speed, called the speed of light. Copyright © Houghton Mifflin Harcourt Publishing Company 12