Elements of Physics Wave Phenomena Teacher s Guide

Transcription

1 Teacher s Guide Grade Level: 6 8 Curriculum Focus: Physical Science Lesson Duration: Two class periods Program Description All energy sound, light, and heat is transmitted as waves. Explore longitudinal and transverse waves and the characteristics they share. Introduce students to the wave-particle duality theory, which holds that matter and energy have characteristics of both waves and particles. Onscreen Questions What are some common characteristics of waves? Why is there no sound in space? What causes a tsunami? How are scientists working to reduce the dangers of a deadly tsunami? Lesson Plan Student Objectives Identify different types of waves. Compare longitudinal and transverse waves. Create a visual presentation to demonstrate important characteristics of one type of wave. Materials Elements of Physics: video Long rope and slinky Computer with Internet access Color printer Poster board and markers Miscellaneous materials for hands-on demonstrations

2 Teacher s Guide 2 Procedures 1. Ask students to identify and discuss the different types of waves featured in Elements of Physics:. electromagnetic waves (light waves) ocean waves (tsunamis) seismic waves sound waves 2. Ask the class to define the term wave. Remind students that there are two types of waves: longitudinal and transverse. In a transverse wave, the disturbance of the medium through which it travels is perpendicular to its direction of travel. In a longitudinal wave, the disturbance of the medium through which it travels is parallel to its direction of travel. 3. Demonstrate both types of waves for the class. Transverse: Have two students hold opposite ends of a rope. Ask one student to move his or her end of the rope up and down, creating waves. Longitudinal: Have two students hold opposite ends of a slinky. Ask one student to push his or her end of the slinky forward and backward, making some rings bunch up while others spread out. 4. Divide the class into four groups, and assign each group a different type of wave from the list above. Explain that their assignment will be to create a visual presentation to demonstrate the characteristics of their assigned wave type. Students should provide at least one image (such as a diagram, photograph, chart, or illustration) or a hands-on demonstration to answer the following questions: How does this wave carry energy? How is this wave measured? Are these waves longitudinal, transverse, or both? What are the effects of a change in the wave s amplitude, wavelength, or frequency? What causes these waves? What is an example or evidence of how these waves reflect? Describe the speed of these waves. If the speed varies, explain why. How do these waves affect our lives? 5. Give each group time to research the questions for their assigned wave type, and develop visuals to answer these questions for the rest of the class. Students may need assistance identifying and finding resources and materials for their research and presentations.

3 Teacher s Guide 3 6. When the groups have completed their demonstrations, conclude the lesson with a class discussion comparing and contrasting the different types of waves. Assessment Use the following three-point rubric to evaluate students' work during this lesson. 3 points: Students identified different types of waves; showed a strong understanding of the difference between longitudinal and transverse waves; developed a clear, engaging, and accurate demonstration that answered all of the questions about their assigned wave type. 2 points: Students identified different types of waves; showed an adequate understanding of the difference between longitudinal and transverse waves; developed a clear, satisfactory demonstration that answered most of the questions about their assigned wave type. 1 point: Students did not identify different types of waves; showed a weak understanding of the difference between longitudinal and transverse waves; developed an incomplete or inaccurate demonstration that answered few of the questions about their assigned wave type. Vocabulary amplitude Definition: The maximum difference of the disturbance, sometimes called the height of the wave Context: When a loud musical note is created, the amplitude of the wave is greater. electromagnetic waves Definition: Waves of radiation in space with electric and magnetic components Context: Electromagnetic waves travel through space at the speed of light. frequency Definition: The number of wave cycles in a given unit of time; typically measured as the number of waves per second and expressed as a hertz, or Hz Context: Humans can hear sounds from 20 hertz to about 20,000 hertz, which means we can hear frequencies from 20 waves per second to about 20,000 waves per second. longitudinal wave Definition: The disturbance of the medium through which this wave travels is parallel to its direction of travel Context: Longitudinal waves transmit sound.

4 Teacher s Guide 4 seismic waves Definition: Waves from explosions and earthquakes that travel through the Earth Context: Seismic waves travel up to seven times faster than the speed of sound in air. transverse wave Definition: The disturbance of the medium through which this wave travels is perpendicular to its direction of travel Context: If transverse waves were visible, they would look like the waves in a rope or the ripples on the surface of a pond. tsunami Definition: A large, catastrophic ocean wave caused by an earthquake, underwater landslide, volcanic eruption, or the impact of a large meteorite in the sea Context: Thirty minutes after the earthquake, the first wave of the tsunami reached the coast. velocity Definition: The speed of a wave; found by multiplying the wave s frequency and wavelength Context: A wave s velocity is limited by the medium in which it travels. wave Definition: A transfer of energy from one point to another Context: All waves carry energy from one place to another. Academic Standards National Academy of Sciences The National Science Education Standards provide guidelines for teaching science as well as a coherent vision of what it means to be scientifically literate for students in grades K 12. To view the standards, visit this Web site: This lesson plan addresses the following science standards: Physical Science: Motions and forces; Interactions of energy and matter Earth and Space Science: Structure of the earth system Mid-continent Research for Education and Learning (McREL) McREL s Content Knowledge: A Compendium of Standards and Benchmarks for K 12 Education addresses 14 content areas. To view the standards and benchmarks, visit

5 Teacher s Guide 5 This lesson plan addresses the following national standards: Science Physical Sciences: Understands the sources and properties of energy; Understands forces and motion. Science Earth and Space Sciences: Understands Earth's composition and structure. DVD Content This program is available in an interactive DVD format. The following information and activities are specific to the DVD version. How to Use the DVD The DVD starting screen has the following options: Play Video This plays the video from start to finish. There are no programmed stops, except by using a remote control. With a computer, depending on the particular software player, a pause button is included with the other video controls. Video Index Here the video is divided into sections indicated by video thumbnail icons; brief descriptions are noted for each one. Watching all parts in sequence is similar to watching the video from start to finish. To play a particular segment, press Enter on the remote for TV playback; on a computer, click once to highlight a thumbnail and read the accompanying text description and click again to start the video. Curriculum Units These are specially edited video segments pulled from different sections of the video (see below). These nonlinear segments align with key ideas in the unit of instruction. They include onscreen pre- and post-viewing questions, reproduced below in this Teacher s Guide. Total running times for these segments are noted. To play a particular segment, press Enter on the TV remote or click once on the Curriculum Unit title on a computer. Standards Link Selecting this option displays a single screen that lists the national academic standards the video addresses. Teacher Resources This screen gives the technical support number and Web site address. Video Index I. Wave Properties (3 min.) Discover the difference between transverse and longitudinal waves and the common properties shared by all waves.

6 Teacher s Guide 6 II. Sound and Electromagnetism (7 min.) Explore the differences between sound waves and electromagnetic waves. III. How Waves Behave (6 min.) Examine how waves are influenced by distortions, including refraction, reflection, the Doppler effect, and wave interference. IV. The Science of Tsunamis (34 min.) Learn about tsunami warning systems while exploring the causes of tsunamis and the devastating effects of the powerful tsunami in December Curriculum Units 1. Common Characteristics of Waves Q: What is a wave? Q: What is the difference between a transverse wave and a longitudinal wave? A: In a transverse wave, the disturbance of the medium through which it travels is perpendicular to its direction of travel. In a longitudinal wave, the disturbance of the medium through which it travels is parallel to its direction of travel. 2. Hearing Sound Waves Q: What can you describe about the transmission of sound? Q: How is sound transmitted? A: Compression waves transmit sound. A wave of energy moves outward from the sound source, pushing air molecules back and forth parallel to the direction the wave travels. Forced outward, the air molecules next to the sound source bump into other molecules, passing the sound vibrations to them so that the energy of the vibration radiates. These waves carry sound to our eardrums.

7 Teacher s Guide 7 3. Transverse Electromagnetic Waves Q: Where is electromagnetic energy found? A: Possible answers include space, the sun, radio, television, electric lights, and other objects. Q: What is wave-particle duality? A: The wave-particle duality theory holds that matter and energy have characteristics of both waves and particles. 4. Wave Distortions Q: What creates an echo? Q: Describe constructive interference and destructive interference. A: Wave interference occurs when two waves traveling in the same medium meet. If the displacement is in the same direction, it is called constructive interference, and the amplitude increases temporarily as the waves pass each other. Similar sound waves complement each other and produce a louder sound, which often happens when musical instruments are played together. Destructive interference occurs when waves overlap, and the displacements are in the opposite direction. This results in either silence or a softer sound. 5. Southeast Asia s Tsunami Q: What caused the tsunami in Southeast Asia in December 2004? Q: Why didn t the countries around the Indian Ocean know about the oceanic earthquake? A: The countries surrounding the Indian Ocean are not part of the Pacific Tsunami Center warning system, and they did not have a warning system of their own.

8 Teacher s Guide 8 6. A Tsunami Survivor s Story Q: What are the effects of a major storm? Q: Is a tsunami one large wave? A: A tsunami is always more than one wave. Its subsequent waves are usually bigger and more powerful. They can be as long as one hundred miles from front to back. The lull between waves can be up to half an hour, deceiving people into thinking that the worst is over, when in fact it is yet to come. 7. Potential Tsunami Scenario Q: Could a tsunami occur anywhere in the United States? Q: Explain the thinking behind the possibility that a tsunami would hit the East Coast of the United States. A: According to one theory, a volcanic collapse of Cumbre Vieja on the Spanish Canary Island of La Palma could cause a landslide so immense it would send a tsunami barreling 3,000 miles toward the United States. It would hit the East Coast, flooding everything from Miami to Boston. The geological history of the volcano gives the theory weight. Cumbre Vieja has had a partial collapse and is said to be under great pressure. The two kinds of rock that make up the volcano work together to trap water. Scientists reason that the heat from a volcanic eruption could raise the pressure of the trapped water, which could force a collapse. An entire side of the volcano would plunge into the sea, unleashing a tsunami. 8. The Pacific Tsunami Center Q: Is it possible to predict major natural disasters accurately? Q: Why might a large undersea earthquake not create a tsunami? A: An earthquake deep within the Earth does not create a tsunami. An earthquake closer to the Earth s surface creates a tsunami.