Unit 1 Lesson 1 Waves. Copyright Houghton Mifflin Harcourt Publishing Company

Transcription

1 Copyright Houghton Mifflin Harcourt Publishing Company

2 B.I - Waves transfer energy and interact in predictable ways. E.Q - What are waves?

3 What are waves? Riding the Wave Waves are disturbances that transfer energy from one place to another. Travel by disturbing (vibrating) a medium. A medium is the material through which a wave can travel. Waves TRANSFER ENERGY Some waves, such as ocean and sound waves, transfer energy through a medium. Some waves, such as light waves, can transfer energy without a medium. p6

4 What are waves? Different Ways to Transfer Energy p7 Waves are disturbances that transfer energy from one place to another. When a wave moves through a medium, particles that make up the matter of the medium vibrate, causing the nearby particles to start vibrating, but they DO NOT change their position (much). Instead the particles return to nearly the same spot they had been in originally.

5 How does a wave transfer energy? Different Ways to Transfer Energy p7

6 Riding the Wave p8 How does a wave 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. Longitudinal Transverse

7 p8 How do waves transfer energy? Energy can be transferred from one object to another using compressions, when the coils are close together, and rarefactions, when the coils are far apart. This causes energy to travel in a longitudinal wave. Longitudinal waves move the medium parallel to the direction in which the waves travel. Sound waves are longitudinal waves.

8 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 perpendicular to the direction the wave travels. p9 The points where a wave is highest are called crests. The points where a wave is lowest are called troughs.

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10 p10 Making Waves What are some types of waves? Waves can also be classified by what they are travelling through. Waves that require a medium, such as water waves, are called mechanical waves. Some mechanical waves can travel through more than one medium. Waves travel at different speeds in different media. Mechanical waves can t travel without a medium.

11 p10 What are some types of waves? Light and similar waves are called electromagnetic (EM) waves. An electromagnetic wave is a disturbance in electric and magnetic fields. Do not require a medium to travel. Sunlight is an example of EM waves. Other examples include radio waves, microwaves, and X-rays. In empty space(vacuum), all EM waves travel at the same speed, called the speed of light 300,000,000 m/s

12 Visualize it! Pg 11 p11 Sunlight is a(n) Water waves are A towel waving displays a(n) Vocal sounds are Music is a(n) Firelight is a(n)

13 Visual Summary p12 15) The water particles in the wave move to the right, along with the wave The water particles in the wave move mostly up and down 16) The toy above and the toy below both show longitudinal waves The toy above shows a longitudinal wave, but the toy below shows a transverse wave 17) This picture shows only examples of mechanical waves. This picture shows mechanical waves (ocean waves) and electromagnetic waves (light EM spectrum)

14 Visual Summary p12 18) Use the example to support the following statement: Waves transfer energy but not matter. A toy on the surface of the pool of water will bob up and down as waves pass.

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16 Waves transfer energy, not matter. Matter, in this case the water and t cork, returns to its original position once a wave has passed. The waves we observed passed through a medium: water. Sound waves are mechanical waves that travel through the air. When we talk or play an instrument, sound waves travel through the air and can be heard by our ears.