Elements of Physics Light: Optics and Electricity Producer/Director Wendy Loten Animation and Graphics Wesley Cudlip Educational Consultants Daniel Coté, MSc Dr. David Harrison University of Toronto Physics Department Editor Gina Binetti Writer/Researcher Bill Freeman, Ph.D. Teacher’s Guide Bill Freeman, Ph.D. Distributed by.. 800.323.9084 | FAX 847.328.6706 | www.unitedlearning.com This video is the exclusive property of the copyright holder. Copying, transmitting, or reproducing in any form, or by any means, without prior written permission from the copyright holder is prohibited (Title 17, U.S. Code Sections 501 and 506). © 2003 Algonquin Educational Productions Table of Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . .1 Links to Curriculum Standards . . . . . . . . . .1 Student Objectives . . . . . . . . . . . . . . . . . . .1 Summary of the Program . . . . . . . . . . . . . .2 Pre-Test and Post-Test . . . . . . . . . . . . . . . . .3 Teacher Preparation . . . . . . . . . . . . . . . . . .4 Student Preparation . . . . . . . . . . . . . . . . . . .5 Description of Blackline Masters . . . . . . . .5 Answer Key . . . . . . . . . . . . . . . . . . . . . . . .6 Discussion Questions . . . . . . . . . . . . . . . . .9 Extended Learning Activities . . . . . . . . . . .11 Reference List . . . . . . . . . . . . . . . . . . . . . . .12 Script of Narration . . . . . . . . . . . . . . . . . . .13 This video is closed captioned. 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Elements of Physics Series Light: Optics and Electricity Grades 9 to 12 Viewing Time: 20 minutes INTRODUCTION Light: Optics and Electricity is part of the Elements of Physics Series, a six-part series of programs designed to help students understand fundamental concepts of physics.The attractive images and engaging narration of the programs have been designed by educators and filmmakers to help students understand the sometimes complicated and obscure scientific explanations of our physical world. The study of light was difficult for physicists because of its incredible speed, but once a theoretical understanding was achieved it led to our development and use of electricity and a whole range of electronic devices. This program focuses on the way that physicists understand and explain light, optics, and electricity and provides a comprehensive introduction to this fascinating area of science. LINKS TO CURRICULUM STANDARDS Elements of Physics Series, is based on the "National Science Educational Standards" for "Physical Science," grades 9-12, (Content Standard B). STUDENT OBJECTIVES After viewing the program and participating in the various follow up activities, students should be able to do the following: • Describe how we see objects either by light reflected from their surfaces or because they are luminescent. • Define the angle of incidence and the angle of reflection in mirrors. • Explain how convex mirrors cause light rays to diverge and concave mirrors cause the rays to converge. 1 • Explain what causes refraction and how it is the basis of a wide variety of optical devices from telescopes to magnifying glasses and the lenses in our eyes. • Describe the principles of concave and convex lenses and how they can correct faults in eyes. • Describe how light breaks into the colors of the spectrum when it passes through a prism. • Give a general explanation of the electromagnetic theory of light. • Describe the electromagnetic spectrum and explain how wave frequencies determine the nature of the wave. • Explain why physicists think the speed of light is one of the fundamentals of the universe. • Define the importance of the light-year as a unit of measurement in the study of the universe. • Explain the relationship between the electromagnetic spectrum and technologies such as radio, television, cellular telephones, telecommunications satellites, microwave ovens, radar, and X-rays. • Illustrate how electricity is generated and transported. SUMMARY OF THE PROGRAM The study of light has long been a fascination of physicists, but it has only been in the last 150 years that an adequate understanding has been achieved. It was in the area of optics that the first breakthroughs were made. We see objects because light is reflected off their surfaces to our eyes. Light bulbs, on the other hand, are luminescent; they generate their own light by electricity. 2 Physicists who studied mirrors learned that the shape of the mirror shaped the image that was reflected from its surface. Refraction is an optical distortion of the image caused by light traveling at different speeds in different mediums. Refraction is the basis of optical devises such as magnifying glasses, eyeglasses, and even the lenses in our eyes. It was not until the middle of the 19th century that physicists gained significant insights into the nature of light. James Clerk Maxwell showed that electricity and magnetism were linked in one of the basic forces of nature called the electromagnetic spectrum. The spectrum ranges from gamma rays, with the highest wave frequency, to radio waves, the slowest. Visible light is a narrow band in the middle of the electromagnetic spectrum. Einstein, developing on the work of Maxwell, demonstrated that the speed of light was one of the fundamentals of the universe. In the last century and a half, scientists and inventors have learned to harness the electromagnetic spectrum for our own use. Radio and television are broadcast using radio waves; telecommunications satellites pass signals from the surface of the Earth to the satellite and back to Earth again; microwaves are used in radar, cell phones, and ovens; and X-rays and infrared rays use waves of higher frequency. Electricity is by far the most important application of our understanding of electromagnetism. Its development has truly revolutionized our way of life. PRE-TEST AND POST-TEST Blackline Master #1, Pre-Test, is an assessment tool intended to gauge student comprehension prior to viewing the program. Remind your students that these are key concepts upon which they should focus while watching the program. Blackline Master #7, Post-Test, can be compared to the results of the Pre-Test to determine the changes in student comprehension after participation in the activities and viewing the program. 3 TEACHER PREPARATION Before presenting this program to your students, we suggest that you preview the program and review this guide and accompanying Blackline Master activities in order to familiarize yourself with the content. Feel free to duplicate any of the Blackline Masters and distribute them to your students. As you review the materials presented in this guide, you may find it necessary to make some changes, additions, or deletions to meet the specific needs of your class. We encourage you to do this. Only by tailoring this program to your class will your students obtain the maximum instructional benefits afforded by the materials. We suggest that you first show the program in its entirety to your students. This is an introduction to the complex subject of light, and at this stage it is helpful that students gain an overview of the concepts and material in the program. A number of lesson activities will grow out of the content of the program and, therefore, the presentation should be a common experience for all students. After the introduction the program is divided into chapters with the following titles:. • Optics • Refraction • What is Light? • The Speed of Light • Putting the Electromagnetic Spectrum to Use • Electricity These chapters vary in length from three to five minutes. After the students have seen the entire program, lessons could be designed around these different chapters. A chapter could be shown at the beginning of the class, and the balance of the class time, and subsequent classes, could be spent examining the subject matter in the program in greater depth. 4 STUDENT PREPARATION It is important that students work through the material and familiarize themselves with the vocabulary, concepts, and theories that scientists use to understand this field. If the students have a textbook that they are following, assign the relevant reading before the lesson. As students work through the material, they will encounter a number of unfamiliar words and concepts. Most of these words are highlighted in the program. An additional list of words is provided in Blackline Masters #2a-c, Vocabulary Definitions and Activities. The program concludes with a 10-question Video Quiz that may be used to gauge students' comprehension immediately after the presentation of the program. Blackline Master #6, Video Quiz, is a printed copy of the questions, which may be reproduced and distributed to the students. The answers to the questions appear in the answer key of this Teacher's Guide. DESCRIPTION OF BLACKLINE MASTERS Blackline Master #1, Pre-Test, should be given to students before viewing the program. When these answers are compared to the Post-Test results, it will help you gauge student progress. Blackline Master #2a, Vocabulary Definitions, will introduce students to unfamiliar words and concepts used in this program. Blackline Master #2b, Use the Right Word, and Blackline Master #2c, Word Match, are activities designed to help reinforce key concepts and vocabulary. Blackline Master #3, Connected/Not Connected, will help students identify their knowledge of key vocabulary terms and the context in which they are used. Blackline Master #4, Crossword Puzzle 5 Blackline Master #5, Creative Writing Story Ideas, will allow students to think creatively while incorporating scientific principles and vocabulary covered in this program. Blackline Master #6, Video Quiz, is a printed version of the Video Quiz that appears at the end of the program. Blackline Master #7, Post-Test, may be used to evaluate student progress after completing this lesson. ANSWER KEY Blackline Master #1, Pre-Test 1. false 2. true 3. true 4. false 5. false 6. false 7. true 8. true 9. false 10. false Blackline Master #2b, Use the Right Word 1. optics 2. refraction 3. luminescent 4. light-year 5. convex 6. electromagnetism 7. insulators 8. reflecting 9. X-rays 10. electricity 6 Blackline Master #2c, Word Match concave a lens or mirror curved inward convex a lens or mirror curved outward electromagnetism waves of electricity and magnetism focus point at which light rays come together light-year distance light travels in a year luminescent objects that radiate light prism disperses light into colors of the spectrum radio waves electromagnetic waves used in telecommunication reflection image thrown back by a barrier visible light electromagnetic waves that allow vision Blackline Master #3, Connected/Not Connected 1. incidence reflection 2. convex concave 3. refraction medium 4. mirrors lenses 5. prisms visible 6. radio gamma 7. electric luminescence 8. light-year space 9. radar cellular phones 10. conductors insulators 7 Blackline Master #4, Crossword Puzzle 1 3 4 I N S U A T O R 5 E 9 L L F I R G A H C O N D U C T 6 7 O F Q L M U E I E C C O N O Y W N C N R F I O 2 S E T C U E C O C R R 11 O A V E V E 8 X 10 R T A D I A O Y N O S V 12 O 13 P E R I S M S I B L T 14 V I E C S Blackline Master #6, Video Quiz 1. true 2. reflection 3. false 4. refraction 5. true 6. true 7. frequencies 8. false 9. true 10. insulators Blackline Master #7, Post-Test 1. focus 2. electromagnetic 3. microwaves 4. light-year 5. false: Depending on the shape of the lens, they can either converge or diverge light. 8 6. false: Telecommunications signals are carried by electromagnetic waves. These signals are usually radio or microwaves. Standard telephones operate with electricity. 7. true 8. false: Both are electromagnetic waves, but gamma rays have the fastest wave frequencies in the electromagnetic spectrum while radio waves are the slowest. 9. false: Conductors are materials that enhance the flow of electricity while insulators stop or inhibit the flow. 10. Light travels at different speeds in different mediums. For example, because air is less dense than water, light travels faster in air than water. This creates a distorted image and the object appears bent or broken at the point where the two mediums meet. This is called refraction and is the basis of all lens technology. 11. When an electron changes direction the oscillations generate electromagnetic waves of energy that are propagated at the speed of light. These electromagnetic waves range from gamma rays, with very high frequencies, to radio waves that have much lower frequencies. Visible light is a narrow band, containing all of the colors, in the middle of the electromagnetic spectrum. 12. Einstein said that matter and energy could not travel faster than the speed of light. If something traveled at those speeds it would literally arrive before it left and that is impossible. The only thing that is able to travel at the speed of light is electromagnetic waves in the vacuum of space. DISCUSSION QUESTIONS 1. What is the similarity between the stars, the sun, molten metal, and a light bulb? They are all luminescent. They generate and radiate electromagnetic waves, which we can see as a form of light. Objects such as buildings, trees, people, the moon, and planets we see as light reflected off their surfaces. 2. Are there different types of telescopes? Yes, there are a great variety of telescopes. In the 16th century, glass-manufacturing techniques greatly improved. Galileo developed a telescope using glass lenses to look at the stars. Others improved on this technique but they found that larger 9 and larger lenses were needed to increase the magnification. Newton solved this problem by using mirrors to focus the image and since his day most telescopes are based on this principle. Today there are even a greater variety of telescopes. Radio telescopes study radio waves from the stars and infrared telescopes have been built. One of the most important recent developments in astronomy came when the Hubble Telescope was placed in orbit. For the first time a telescope was raised above the distorting effects of the Earth's atmosphere and it has produced a spectacular series of images of the heavens. There are now plans to place a telescope in deep space outside the orbit of the Earth altogether. 3. What is the relationship between science and the technical instruments that help us study nature? Our ability to provide scientific explanations has always been limited by our ability to observe. Astronomy is one of the best examples of this. Our understanding of the universe, and our explanations of how it was formed and developed, has been limited by the telescopes and other instruments we have to observe the heavens. Scientific theory and empirical observation are both essential to the development of science. 4. The television program "Star Trek" suggests that the "Starship Enterprise" can travel faster that the speed of light in what they call warp-speed. Is that possible? Not according to Einstein and the best physicists of our day. The theory of relativity concludes that at the speed of light, matter would disintegrate into sub-atomic particles, and if anything traveled faster than the speed of light it would arrive before it left. "Star Trek" is truly in the realm of science fiction. 5. Will the speed of light be a limitation to space travel? Yes. It is possible to imagine that we can travel to planets within our solar system, but even here the distances are enormous and the time to travel to distant stars and planets would take years. The distances beyond our solar system are almost impossible to imagine. Alpha Centuri, our closest star beyond the sun, is 4.3 light-years away, and the center of the Milky Way Galaxy is estimated to be 27,000 light-years away. Travel to any place beyond our solar system would take centuries. But even if we 10 do not travel to distant stars, astronomy has shown we can learn a great deal about the universe from here on Earth. EXTENDED LEARNING ACTIVITIES The following activities and projects might prove useful to students studying the subject of light, optics and electricity. 1. Set up a flat mirror at an angle to the point of observation. Calculate the angle of incidence and the angle of reflection. Write a report describing your experiment, how you preformed your calculations, and your conclusions. 2. Study convex and concave lenses. Draw diagrams showing what happens to the light rays as they go through each lens and write captions to the diagrams explaining the phenomena. 3. Draw diagrams showing how optometrists use lenses to correct the vision of near-sighted and far-sighted patients. Explain some of the other vision problems that people experience and how they can be corrected with lenses. 4. Draw a diagram of the electromagnetic spectrum and explain why visible light is only a small part of the phenomenon of light. 5. Calculate the distance in miles or kilometers between the solar system of the sun and three of our nearest stars. If an astronaut can travel at half the speed of light, how long will it take him or her to arrive in the vicinity of these stars? What limitation does this place on space travel? Are there any solutions? 6. Research two different types of telescopes. Describe how they work and explain the advantages and disadvantages of each of them. 7. Visit a planetarium or observatory that is open to the public. Report on some interesting aspect of the presentation such as space travel, distances of the stars, or the origins of the universe. 11 8. Visit a television station and describe the technology of how the program is transmitted and then received into your home. 9. Current affairs, television, and radio programs often feature a host talking to a journalist on the other side of the world about a fast breaking story. The host will ask a question and there is a noticeable pause before the journalist replies. What is the reason for that pause? Is there any way that it can be avoided? Report on your findings and conclusions. 10. Research the way the electricity received in your community is generated. Write a report showing how your city, town, or countryside could develop an electric generating system that is less polluting than the one in use. What are the advantages and disadvantages of the system that you have designed? REFERENCE LIST There are many excellent books and websites dealing with light, optics and electricity that are appropriate for students and available in libraries. The following is a short list. Books: Physics, A Practical Approach, Hirsch, Alan J., Second Edition, New York: John Wiley and Sons, 1991. Physics, Huber-Schaim, Uri, John H. Dodge, James A. Walter, Fifth Edition, Lexington, Mass.: D.C. Heath and Co., 1981. Basic Physics: A Self-Teaching Guide, Kuhn, Karl F., Second Edition, New York: John Wiley and Sons Inc., 1996. Physics, Principles and Problems, Zitzewitz, Paul W., New York: Glenco-McGraw-Hill, 1999. Internet Sites: http://www.aapt.org This is the website of the American Association of Physics Teachers, an organization of physics high school teachers. They also publish a magazine called The Physics Teacher. 12 http://enrich.sdsc.edu/SE/opticsintro.html This site is prepared by the Science Enrichment Program and designed for students. It has detailed information on various optical devises and excellent diagrams. http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum html This is one of the best sites that describes the electromagnetic spectrum. The diagrams are easy to understand and the text is clear. www.colorado.edu/physics/2000/waves_particles/wpwaves5.ht ml This excellent website was prepared by the University of Colorado. It has detailed information about quantum physics and is particularly good on electromagnetism. \ SCRIPT OF NARRATION The study of light has been central to physics since the days of the Ancient Greeks, but despite the remarkable strides in our understanding there are still debates as to its true nature. We are going to review the way physicists understand light by looking at optics, electromagnetism, and the speed of light. The program will illustrate the way these theoretical understandings have led to the development of our use of electricity and other electronic devices. OPTICS We see objects either because light is reflected off their surfaces to our eyes or because the objects themselves are luminescent. We can see the moon, for example, because light from the sun is reflected off its surface. Amusement rides, flowers, and birds - we see all of these objects because light is reflected off their surfaces to our eyes. But a neon sign, or a light bulb is luminescent; they generate their own light by electricity. In nature, we often see examples of light being reflected, as on the surface of water, or polished surfaces. Mirrors offered sci13 entists a way to study reflection and early experiments showed that light travels in a straight line and bounces off mirrors in predictable ways. Physicists discovered that the angle at which the light ray strikes the surface, called the angle of incidence, is equal to the angle at which it bounces off, called the angle of reflection. Moving the mirror changes which rays are reflected into our field of view. By moving the mirror we can see what is behind us without turning our heads! Changing the shape of the mirror from flat to convex causes the reflected light rays to diverge. On the other hand, a concave mirror causes the light rays to converge and intersect at a point called the focus. In both of these cases, light is obeying the laws of reflection. The light travels in a straight line but the shape of the mirror distorts the reflected image. REFRACTION Another phenomenon of light is called refraction. This pencil appears broken at the water line. The reason this happens is because light travels at different speeds in different mediums. Air is a less dense medium than water and light waves travel faster through air than through water. When the light meets the boundary of the new medium at an angle, the light wave is bent before continuing in a straight line. This creates the distorted image. Both reflection and refraction involve a change in direction of a wave, but only refraction involves a change in medium. The refraction of light is the basis of optical devices such as eyeglasses, magnifying glasses, binoculars and even the lenses in our own eyes. When light enters the new medium of the lens, its speed is slowed and the light ray is refracted, when it enters and also when it leaves. Some lenses are convex, and cause the light rays to converge; others are concave and cause the light to diverge. The refracted light rays can be focused by the lens to form an image. In our eyes, muscles can change the shape of the lens 14 and focus the image clearly on the optic nerve at the back of the eye. Sometimes the shape of the lenses of our eyes doesn't focus the image clearly and our vision is blurred. Specially shaped glasses correct this fault. By using different combinations of lenses and mirrors to form images, we can make all sorts of optical devices from cameras to microscopes. The early telescopes were all built with lenses but they were limited by the physical size of the lens. All of the large optical telescopes in use today are reflecting telescopes that use mirrors to focus the light. One of the most interesting devices that refracts light is a prism, an angled piece of glass. Notice how the white light is broken into the spectrum of the rainbow: seven colors: red, orange, yellow, green, blue, indigo, and violet. Why does this happen? The reason was only discovered when scientists were able to understand the complex nature of light. WHAT IS LIGHT? What is light? It took until the middle of the nineteenth century before some of the basic questions were answered. In 1873, James Clerk Maxwell, a British physicist, developed equations based on the link between electric fields and magnetic fields. The oscillations, or movements back and forth of electric charges within these fields generate electromagnetic waves of energy. Maxwell's calculations of the velocity of these waves matched the speed of light and led him to predict that light is a form of energy that travels as an electromagnetic wave. The electromagnetic spectrum consists of bands of waves that have different frequencies. From the highest frequency waves with the highest energy to the lowest frequency with the lowest energy, the waves range from gamma rays, X-rays, ultra violet rays, visible light, infra-red rays, micro waves to radio waves. What we call light - or visible light - is only a narrow band in the electromagnetic spectrum. Included in that band are all of the colors. Each of the colors has a different wavelength. The longest wavelength is the color red 15 and the shortest, violet. Because of the different wavelengths, the light rays bend at a different rate when they go through the prism and create the rainbow. The tremendous energy coming from the sun is the greatest source of electromagnetic radiation in our solar system but we can also generate light ourselves here on Earth. Fire is a source of electromagnetic energy. The chemical reaction of burning releases electromagnetic radiation that we see as light. Electric lights become luminous when electricity flows through the filament in the bulb, causing it to heat and glow when it is brought to a high enough temperature. THE SPEED OF LIGHT Light travels so fast that it was once thought that it was instantaneous. But in 1673, the speed of light was first successfully measured after many observations of the orbiting moon of Jupiter. Light, it was found, took time to travel across space. In the early 1900s, while working on different aspects of the theory of relativity, Albert Einstein concluded that the speed of light was one of the fundamentals of the universe. Einstein said that matter and energy could not travel faster than the speed of light because as matter accelerates, its mass increases and more energy is required to accelerate it further. As it approaches the speed of light, the energy requirements become infinite. This makes it impossible for any mass to travel faster than light. After research over many years it has been determined that the speed of light through the vacuum of space is 299,792.458 kilometers per second, or 186,282.4 miles per second. If you could travel at the speed of light, you could go from London, England to Los Angeles, California in less than one-twentieth of a second! Imagine how far light travels in the vacuum of space in one year. This is called a light-year, and is now used as the world's standard for measuring distance because it never varies. Astronomers use the measurement of the light-year to calculate the vast distances between objects in space. Our solar system is in the Milky Way Galaxy, which is made up of about 100 billion stars. This disk-shaped galaxy is about 100,000 light16 years across and we live about 27,000 light years from the center. Astronomers believe there are billions of galaxies, some as far away as 10 billion light-years. When we look at the night sky we are seeing ancient light that has taken so long to reach us, the stars that produced it may no longer exist. PUTTING THE ELECTROMAGNETIC SPECTRUM TO USE In the last 150 years, scientists and inventors have built on the understanding of the differing wavelengths and frequencies of the electromagnetic spectrum to develop a dizzying array of technologies that have benefited all of us. Radio waves have the lowest frequency in the electromagnetic spectrum. When a radio program is broadcast an antenna sends out radio waves at a certain frequency - or number of waves per second. Every radio station has its own frequency. When we tune in a station what we are doing is adjusting our radio to the same frequency of the radio wave broadcast from the station's antenna. When they are both on the same frequency our radio receives the signal from the station and transforms it into sound waves, which we can hear. Many radio waves can be broadcast at the same time. As long as they are transmitted on different frequencies, none of them will interfere with the others. Television works in much the same way but the frequencies are higher in the electromagnetic spectrum. An electric signal carrying information about the image arrives at the back of the television tube. Those signals send electrons to the front of the tube creating dots of light on the screen. Those dots are quickly assembled as an image, which changes so quickly it appears to move and provide action. The curvature of the Earth limits the reception range of telecommunication signals since electromagnetic waves usually travel in a straight line. In recent years, satellites have been placed in orbit high above Earth to get around this problem. Signals are sent from Earth to the satellite and back to Earth again. In this way signals can be sent all over the globe. 17 Increasingly electromagnetic waves with higher frequencies are being used. The signals in cellular phones and telecommunication transmitters are microwaves. The same type of wave is used in microwave ovens. Radar is another use. It was developed in the Second World War to detect incoming enemy airplanes. Microwaves are sent out from a tower. The beams bounce off incoming aircraft and some of the signal returns to the tower. Instruments read this signal to give the location of the aircraft, its speed and direction. Today, radar is an essential tool for defense and civil aviation. Infrared rays have been adapted to help people see in the dark. Ultraviolet is used in florescent lighting. X-rays are used for dental and medical applications because their short wavelengths can penetrate soft tissue and show bones. The difficulty in using the waves that are higher in the spectrum is that they can be dangerous to humans. Overexposure to Xrays, for example, can lead to serious medical problems. But the more that is learned about electromagnetism the more applications are found. ELECTRICITY By far the most useful application of electromagnetism has been the development of electricity. The key to understanding electricity is in atoms, the basis of all matter. Atoms consist of negatively charged electrons that orbit around a nucleus made up of positively charged protons and neutral neutrons. It is the movement of the electrons that generate changes in electromagnetic fields of energy that is electric power. In 1831, Michael Faraday, a British scientist, demonstrated that electricity could be generated when a magnet was moved inside a coil of wire. Moving the magnet one way in the coil causes the electrons in the wire to flow in one direction. When the magnet moves back again, the electrons reverse and flow in the opposite direction. What is created in this process is an alternating electric current. The application of this research led to the commercial development of electricity. 18 But how is the electricity transported? Opposite electrical charges attract and like electrical charges repel each other. Electrons have a negative charge and they can jump from atom to atom and molecule to molecule. When there is a build up of electrons they will be attracted to positively charged protons. When a negative charge has built up in one location and a positive charge in another location, and if they are connected with a good conductor, the negatively charged electrons will flow along the conductor to the positive charge. There are some materials that are good conductors of electrons like metals, water and the human body. Insulators are the opposite of conductors; they are materials that inhibit the flow of electrons. Examples include rubber, plastics, paper and glass. The copper of an electric wire is an excellent conductor. It is covered with a plastic coating, which is a good insulator. The conductor allows the electrons to flow along it but the insulator stops the electric power from leaking out. Understanding of these basic principles lead to the rapid development in the technology of electricity, which has transformed our lives. By 1873, it was shown how electric power could be transmitted through wires, and in 1879, Thomas Edison, the American inventor, developed his incandescent light bulb. By 1900, electric power was being widely used in North America and Europe and today electric power is used in virtually every part of the globe as the source of energy for a wide variety of uses. Most electricity used today is still generated by turning a magnet within a coil of wire. This takes a tremendous amount of mechanical energy that can be provided in a number of different ways. The waterpower of Niagara Falls was one of the earliest sources of power in North America. Windmills or steam driven turbines heated by nuclear power or fossil fuel such as coal and natural gas can also generate electric power. Today we use electricity to drive complicated machinery in factories, various types of vehicles and as a source of power to run a wide range of household appliances. The benefits that we 19 have received from the efforts of physicists in unlocking the mysteries of light, electromagnetism, and electricity have been truly amazing. 20 1 Name ____________________ ELEMENTS OF PHYSICS LIGHT: OPTICS AND ELECTRICITY Pre-Test Directions: This will help you discover what you know about the subject of light optics and electricity before you begin this lesson. Answer the following true or false. 1. We always see objects because light is reflected off their surfaces. T_______ F_______. 2. A light bulb is luminescent because it radiates light. T_______ F_______. 3. The angle of incidence of a mirror is equal to the angle of reflection. T_______ F_______. 4. Refraction is a reflected image. T_______ F_______. 5. Convex mirrors cause light rays to converge. T_______ F_______. 6. The electromagnetic spectrum only contains visible light. T_______ F_______. 7. Physicists believe matter cannot travel faster than the speed of light. T_______ F_______. 8. A light-year is the distance light can travel in a vacuum in a year. T_______ F_______. 9. Radio waves run microwave ovens. T_______ F_______. 10. Insulators conduct electricity. © 2003 Algonquin Educational Productions T_______ F_______. Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 2a Name ____________________ ELEMENTS OF PHYSICS LIGHT: OPTICS AND ELECTRICITY Vocabulary Definitions The following words and terms used in the program may be unfamiliar to you. Try to listen for these terms while viewing the program, pay close attention so you can later include them in your scientific descriptions, observations, and creative writing assignment activities. angle of incidence - the angle at which the image strikes luminescent - objects that radiate light. a mirror. Maxwell, James Clerk - British physicist, 1831 - 1879. angle of reflection - the angle at which the image is reflected off a mirror. medium - an intervening substance that allows energy to pass such as air, water, or solids. Aristotle - ancient Greek philosopher, 384 - 322 BC. microwaves - electromagnetic waves used in cellular concave - a lens or mirror curved inward. phones, radar, and ovens. conductor - conducts electricity. convex - a lens or mirror curved outward. Edison, Thomas - American inventor, 1847 - 1931. neutrons - part of the nucleus of atoms with no electrical charge. optics - branch of physics dealing with light and vision. photons - sub-atomic particles of energy and matter Einstein, Albert - German-American physicist, 1879 - propagated by electromagnetic waves. 1955. prism - a glass or crystal with equal sides that can diselectromagnetic spectrum - includes all of the electro- perse light into the colors of the spectrum. magnetic waves with different wavelengths and frequencies. protons - positively charged part of the nucleus of atoms. electromagnetism - waves of electricity and magnetism, often called light. radio waves - electromagnetic waves used in telecommunications. electrons - negatively charged particles that orbit the nucleus of atoms. reflecting telescope - a telescope where the image is enlarged by mirrors. Faraday, Michael - English chemist and physicist, 1791 - 1867. reflection - an image thrown back by a barrier like a mirror. focus - point at which light rays come together. refraction - because light travels in different speeds in frequency - number of waves in a given unit of time. different mediums, objects appear broken or refracted, where the two mediums meet. Refraction is the basis of gamma rays - the fastest waves in the electromagnetic lens technology. spectrum. ultra violet rays - electromagnetic waves used for infrared rays - electromagnetic waves used for heating florescent lighting and heating. and seeing in the dark. visible light - electromagnetic waves in the middle insulators - inhibit the flow of electricity. of the spectrum that give visible light. light-year - the distance that light travels in a vacuum in X-rays - electromagnetic waves used in dental and one year. medical imaging. © 2003 Algonquin Educational Productions Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 2b Name ____________________ ELEMENTS OF PHYSICS LIGHT: OPTICS AND ELECTRICITY Use the Right Word Directions: Find the right word from the physics vocabulary list that completes the following sentences. 1. The branch of physics dealing with light and vision is called ____________. 2. ____________ is the basis of lens technology. 3. Objects that radiate light are ____________. 4. A ____________ is the distance that light travels in a vacuum in one year. 5. A lens or mirror curved outward is called ____________. 6. Waves of electricity and magnetism are called ____________. 7. ____________ inhibit the flow of electricity. 8. A ____________ telescope enlarges the image with mirrors. 9. The electromagnetic waves used in medical imaging are called ____________. 10. ____________ is usually generated by rotating a magnet in a coil of wire. © 2003 Algonquin Educational Productions Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 2c Name ____________________ ELEMENTS OF PHYSICS LIGHT: OPTICS AND ELECTRICITY Word Match Directions: Connect the word with the proper definition. concave distance light travels in a year convex objects that radiate light electromagnetism image thrown back by a barrier focus a lens or mirror curved inward light-year electromagnetic waves used in telecommunication luminescent electromagnetic waves that allow vision prism waves of electricity and magnetism radio waves point at which light rays come together reflection disperses light into colors of the spectrum visible light a lens or mirror curved outward © 2003 Algonquin Educational Productions Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 3 Name ____________________ ELEMENTS OF PHYSICS LIGHT: OPTICS AND ELECTRICITY Connected/Not Connected Directions: Place the following words in the proper sentences. cellular phones concave conductors convex electric gamma incidence insulators lenses light-year luminescence medium mirrors prisms radar radio reflection refraction space visible 1. The angle of ____________ is connected to the angle of ____________ because both angles are exactly the same. 2. ____________ lenses are NOT connected to ____________ lenses because one causes light rays to converge and the other causes them to diverge. 3. ____________ is connected to ____________ because light travels faster through some substances than others making the image appear bent or broken. 4. ____________ are NOT connected to ____________ because one reflects light and the other causes light to be refracted. 5. ____________ are connected to ____________ light because these angled pieces of glass or crystals break light into a spectrum of seven colors. 6. ____________ waves are NOT connected to ____________ rays because one is the slowest wave in the electromagnetic spectrum and the other is the fastest. 7. ____________ lights are connected to ____________ because they radiate light. 8. The ____________ is NOT connected to ____________ travel because the incredible distances in space that it measures will make this form of travel very difficult. 9. ____________ and ____________ are connected because both use microwaves to transmit their signal. 10. ____________ of electricity are NOT connected to ____________ of electricity because one inhibits the flow of electricity and the other enhances it. © 2003 Algonquin Educational Productions Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 4 Name ____________________ ELEMENTS OF PHYSICS LIGHT: OPTICS AND ELECTRICITY Crossword Puzzle 1 2 3 4 5 6 7 9 8 10 11 12 13 14 Across 1. point at which waves come together 3. material that inhibits the flow of electricity 7. lens or mirror curved outward 9. material that enhances the flow of electricity 10. waves used in television 11. lens or mirror curved inward 13. glass that disperses light into the colors of the spectrum 14. the _________ light of electromagnetic spectrum lets us see Down 1. number of waves in a unit of time 2. thrown back by a barrier 4. the image appears bent where two mediums meet 5. electromagnetic waves 6. electromagnetic waves used in cellular phones 8. electromagnetic waves used in medical imaging 12. dealing with light and vision © 2003 Algonquin Educational Productions Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 5 Name ____________________ ELEMENTS OF PHYSICS LIGHT: OPTICS AND ELECTRICITY Creative Writing Story Ideas Directions: Choose from one of the ideas listed below and write a story or dramatization. Include plot lines that follow scientific principles and key vocabulary terms. 1. You are shipwrecked on a desert island with only a mirror and a convex lens as tools. Tell the story of how you use these instruments for your survival and rescue. 2. Jack Hoggins, genius inventor, works in an electronics store filled with computer games and electronic gadgets. The storeowner asks Jack to design a security system using some of the stuff in the store. Two days after the system is installed, May Squires arrives. Is she intent on plundering the till or testing the system? A little humor might be appropriate as you tell the story of the events of that fateful afternoon. 3. Every evening at dusk, Dr. Peter Becker climbs the 99 steps up the mountain behind his home to his private observatory and every night he studies the heavens. On one particularly clear night something strange happens. Is Dr. Becker witnessing an invasion of space aliens? Should he rush to tell the world or wait to see if these invaders are hostile? Write a radio script dramatizing what happens. 4. A group of eccentric physics graduate students are given the task of trying to find the way to break the most fundamental barrier in the universe - the speed of light. If this can be accomplished space travel will be as easy as air travel is today. Write a science fiction story explaining what happens as they collaborate to achieve their task. 5. Air pollution is choking the life out of a city neighborhood. A citizens group starts a research program to find out what is causing the pollution and to establish a program to eliminate it, but there are very powerful people who are opposed to their actions. As the research continues the truth is revealed. Describe the events. © 2003 Algonquin Educational Productions Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 6 Name ____________________ ELEMENTS OF PHYSICS LIGHT: OPTICS AND ELECTRICITY Video Quiz Directions: Answer the following true or false, or fill in the blank with the correct word to make it true. 1. We see objects either because light is reflected off their surfaces to our eyes or the objects themselves are luminescent. T_______ F_______. 2. The angle at which light rays bounce off a mirror is called the angle of ____________. 3. A convex mirror causes the light rays to converge. T_______ F_______. 4. When an object is suspended in two mediums, like air and water, its image appears broken at the boundary of the mediums. This is called ____________. 5. The sun, fire, and light bulbs are all sources of electromagnetic waves. T_______ F_______. 6. Einstein said that objects can travel faster than the speed of sound. T_______ F_______. 7. As long as radio waves are broadcast at different ____________ they will not interfere with each other. 8. Television is broadcast using gamma rays. T_______ F_______. 9. Exposure to some electromagnetic waves can lead to serious medical problems. T_______ F_______. 10. Materials that inhibit the flow of electricity are called ____________. © 2003 Algonquin Educational Productions Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution. 7 Name ____________________ ELEMENTS OF PHYSICS LIGHT: OPTICS AND ELECTRICITY Post-Test Vocabulary Directions: Fill in the blank with the appropriate term from the list below. concave conductor convex electromagnetic focus frequency gamma insulator lens light light-year microwave optics photons radio reflection refraction television telescope visible 1. The point at which light rays intersect when they are reflected off a concave mirror is called the ____________. 2. The ____________ spectrum consists of bands of waves that have different wavelengths and frequencies. 3. Radar uses electromagnetic waves called ___________________. 4. The distance light travels in one year is called a ____________. True or False Directions: Fill in the blank with True or False. If the statement is false, change it to make the statement true. Rewrite the true statement in the space provided. 5. __________ Lenses can only converge light. 6. __________ The electromagnetic spectrum can never be used for telecommunications. 7. __________ The study of optics deals with light and vision. 8. __________ Radio and gamma waves are the same. 9. __________ Conductors stop the flow of electricity. Essay Section Directions: Answer the following questions in complete sentences. Use the back of this page or a separate sheet of paper if you need more space to complete your answer. 10. Explain why objects appear to be broken at the boundary where two mediums meet. 11. Describe how modern physics explains light. 12. Why did Einstein believe that the speed of light was one of the fundamentals of the universe? © 2003 Algonquin Educational Productions Published and Distributed by United Learning All rights to print materials cleared for classroom duplication and distribution.