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10 Science Quarter 2-Module 1 Electromagnetic Wave Theory 1|Page Quarter 2 – Module 1: Electromagnetic Wave Theory Second Edition, Revised 2021 Republic Act 8293, section 176 states that: No copyright shall subsist in any work of the Government of the Phil...

10 Science Quarter 2-Module 1 Electromagnetic Wave Theory 1|Page Quarter 2 – Module 1: Electromagnetic Wave Theory Second Edition, Revised 2021 Republic Act 8293, section 176 states that: No copyright shall subsist in any work of the Government of the Philippines. However, prior approval of the government agency or office wherein the work is created shall be necessary for exploitation of such work for profit. Such agency or office may, among other things, impose as a condition the payment of royalty. Borrowed materials (i.e., songs, stories, poems, pictures, photos, brand names, trademarks, etc) included in this book are owned by their respective copyright holders. Every effort has been exerted to locate and seek permission to use these materials from their respective copyright owners. The publisher and authors do not represent nor claim ownership over them. Published by the Department of Education – Division of Cebu City Schools Division Superintendent: Rhea Mar A. Angtud, EdD Development Team of the Module Writer: Rommel G. Cinco, Teacher I, Mabolo National High School Content Editors: Dr. Deogenes R. Adoptante, Principal I, Mambaling National HS Mrs. Arnolfa A. Demellites, Principal I, Guba National HS Language Editor: Mrs. Wilma Y. Villaflor, Principal III , Don Vicente Rama Mem. ES Management Team: Dr. Rhea Mar A. Angtud, Schools Division Superintendent Dr. Bernadette A. Susvilla, Asst. Schools Division Superintendent Mrs. Grecia F. Bataluna, CID Chief Dr. Raylene S. Manawatao, EPS – Science Mrs. Vanessa L. Harayo, EPS – LRMDS Printed in the Philippines by Department of Education Division of Cebu City ROVII Office Address: Imus Avenue, Cebu City Telephone Nos: (032) 255-1516 / (032)253-9095, E-mail Address: [email protected] 2|Page  Module Electromagnetic Wave Theory 1 Introduction Did you send text messages to somebody else? Or have you ever tried cooking in a microwave oven? Did you know that these previously mentioned human activities make use of microwaves? Microwaves carry energy, and so with the other kinds of electromagnetic waves. But what are electromagnetic waves? How can these waves become useful to us? At the end of this module, the learners should be able to answer the following questions: 1. What are the properties of electromagnetic wave? 2. How are EM waves different from mechanical waves? Learning competencies/objectives 1. Trace the development of the electromagnetic theory 2. Describe how electromagnetic (EM) wave is produced and propagated. What I Know Multiple Choice: Choose the letter of the correct answer. Write the letter on a separate sheet of paper. 1. A certain radio station broadcasts at a frequency of 675 kHz. What is the wavelength of the radio waves. (Note: 1 kHz = 1000 Hz) A. 280 m B. 324 m C. 400 m D. 444 m 2. All electromagnetic waves travel through a vacuum at A. the same speed. B. speeds that are proportional to their frequency. C. speeds that are inversely proportional to their frequency. D. none of the above. 3. The table below lists the speed of light in four different situations. In which situations is light travelling in a vacuum? 3|Page 4. Which of the following statements best describes an electromagnetic waves with a long wavelength? A. It has a low frequency and can travel in a vacuum. B. It has a high frequency and can travel in a vacuum. C. It has a low frequency and can only travel in a medium D. It has a high frequency and can only travel in a medium. 5. The electric and magnetic fields of an electromagnetic wave are A. in phase and perpendicular to each other B. in phase and not perpendicular to each other C. out of phase and perpendicular to each other D. out of phase and not perpendicular to each other 6. Consider an oscillator which has a charged particle and oscillates about its mean position with a frequency of 300 MHz. The wavelength of electromagnetic waves produced by this oscillator is ______. (Note: 1 MHz = 1,000,000 Hz) A. 1 m B. 10 m C. 100 m D. 1000 m 7. Find the frequency of an electromagnetic wave with a wavelength 2.75 x 10 -8 m. A. 1.10 Hz C. 9.17 x 1015 Hz B. 1.09 x 10 Hz 16 D. 9.17 x 1016 Hz 8. A wave with a low frequency would have relatively ___________. A. high energy and a short wavelength B. low energy and a long wavelength C. high energy and a long wavelength D. low energy and a short wavelength 9. Which of the following graphs best represents the relationship of the frequency of an electromagnetic wave to its wavelength? 10. Which of the following is NOT true for electromagnetic waves? A. It transports energy B. It transports momentum C. It transports angular momentum D. In vacuum, it travels with different speeds which depend on their frequency 11. Find the wavelength of an electromagnetic wave with a frequency of 5.00 × 1014 Hz. A. 1.5 x 10-6 m C. 5.64 x 10-7 m B. 3.00 x 10-8 m D. 6.00 x 10-7 m 12. Compared to the speed of a sound wave in air, the speed of a radio wave in air is ___________. A. Greater C. The Same B. Less D. All of the above 13. Electromagnetic waves are propagated through the interaction of A. Nuclear and Electric Fields B. Electric and Magnetic Fields C. Gravitational and Electric Fields D. Gravitational and Magnetic Fields 4|Page 14. These are waves that are created as a result of vibrations between an electric field and magnetic field. A. Electromagnetic wave C. Microwave B. Electromagnetic spectrum D. Radio wave 15. What is the speed of electromagnetic wave in a vacuum? A. 0 m/s C. 1.13 x 103 m/s B. 3.31 x 102 m/s D. 3.00 x 108 m/s What’s In In your Grade 7, you were able to learn the concepts of waves and its characteristics. Let us review how will you remember these concepts. A. Complete the sentence below with the correct word. Write your answer on your answer sheet. 1. E _ _ _ _ _ travels in waves. 2. Transverse waves move up and down in patterns that have high points called _ _ e _ _. 3. The low points of a transverse wave are called _ r _ u _ h. 4. The distance between any two throughs or peaks is called the _ _ v _ _ _ n _ _ _. 5. The height of a peak or through is called the a _ _ _ _ _ _ d _. 6. _ _ e _ _ e _ _ _ is the number of complete waves that pass by in one second. 7. Frequency is measured in _ _ _ t _ (which is written Hz) 8. L _ _ g _ _ _ d _ _ _ _ waves move by pushing forward and pulling back. 9. _ o _ _ _ waves are examples of longitudinal waves. 10. Waves on the surface of water are examples of t _ _ _ _ _ _ _ _ _ _ waves. B. Label the diagram below. A. __________________ wave B. _______________ wave 5|Page. What’s New Making Some Waves You have probably seen a wave, but have you created one? Let’s try and make some waves. Get a rope of any kind and tie one end of it to a fixed sturdy object near you. Now, straighten the rope and hold the other end of it. Start moving your hands up and down. Observe what happens to the rope. Were you able to make a wave? Draw the wave you made on a separate sheet of paper. Now, try to make a wave again but move your hands slowly. Observe what happens. Draw the image of the wave you created. This time, make a wave while moving your hands fast. Draw the image of the wave. Based on the activity, is there any difference on the waves you have created? Why does each created wave look differently? _______________________________ __________________________________________________________________________________ __________________________________________________________________________________ _____________________________________________________________ 6|Page  What is It When you move your hands up and down while holding one end of the rope, you create wave on the rope. The waves you created may look different depending on how fast you move your hand. Similarly, if you move an electrically charged object back and forth in an empty space, you’ll create electromagnetic waves in space. But what is an electromagnetic wave? THE ELECTROMAGNETIC WAVE THEORY Brief History of Electromagnetic Theory Electricity and magnetism – in physics, these two words often go together like horse and carriage, in electromagnetism and electromagnetic induction. Let us meet the original players in the electromagnetism: Oersted, Ampere, Faraday, Henry and Maxwell along with many others who laid the groundwork for the understanding of the concepts of electromagnetic theory. Danish physicist, Hans Christian Oersted discovered accidentally, 1820 that magnetic needle is deflected when the current in a nearby wire varies – a phenomenon establishing a relationship between electricity and magnetism. Figure 1. Oersted’s setup on the discovery of electromagnetism Andre-Marie Ampere, influenced by Oertsed’s discovery, performed a series of experiments designed to elucidate the exact nature of the relationship between electric current-flow and magnetism, as well as the relationships governing the behaviour of electric currents in various types of conductors. These experiments led Ampere to formulate his famous law of electromagnetism, called after him Ampere’s Law that describes mathematically the magnetic force between two electrical currents. 7|Page  Figure 2. Illustrative explanation of Faraday’s experiment Michael Faraday made his first discovery of electromagnetism in 1821. He took the work of Oersted and Ampere on the magnetic properties of electrical currents as a starting point and in 1831 achieved an electrical current from a changing magnetic field, a phenomenon known as electromagnetic induction. He found that when an electrical current passed through a coil, another very short current was generated in a nearby coil. This discovery marked a decisive milestone in the progress not only of science but also of society, and is used today to generate electricity on a large scale power stations. Joseph Henry, while working with electromagnets in 1829, made important design improvements by insulating the wire instead of the iron core. He was able to wrap a large number of turns of wire around the core and thus greatly increase the power of the magnet. He had made an electromagnet that could support 2 063 pounds, a world record at the time. He also searched for electromagnetic induction and in 1831, he started to build a large electromagnet for that purpose. He was the first to notice the principle of self- induction. A brilliant physicist and mathematician, James Clerk Maxwell, proposed Faraday’s electromagnetic induction to happen even in empty space. The symmetry between the fields fascinated him so much. He added two basic principles of electromagnetism: (1) a changing electric field in space produces a magnetic field, (2) a changing magnetic field in space produces electric field. Maxwell proposed that the alteration of electric and magnetic fields, generating and propelling each other in space, can be thought of as a form of moving energy. Maxwell further thought of this form of energy as a wave which he called electromagnetic wave. Using mathematical computations based on his theoretical assumption and the numerical results of Faraday’s experiments, Maxwell concluded that the speed of electromagnetic waves must be 3 x 108 m/s. It was only after the death of Maxwell which a German physicist, Heinrich Hertz, designed an experimental set up that was electrical in nature and able to generate and detect electromagnetic waves. 8|Page Learning Task 1. Match the scientists given below with their contributions. Scientists Contributions _____ 1. Ampere a. Contributed in developing equations that showed the relationship of electricity and magnetism _____ 2. Faraday b. Showed experimental evidence of electromagnetic waves and their link to light _____ 3. Hertz c. Demonstrated the magnetic effect based on the direction of current _____ 4. Maxwell d. Formulated the principle behind electromagnetic induction _____ 5. Oersted e. Showed how a current carrying wire behaves like a magnet Electromagnetic Waves We are surrounded with thousands of waves. They collide with our bodies and some pass through us. Mostly are invisible but we can perceive some. The warmth of the sun and the light that we see are just few of them. These waves share similar characteristics, yet, they are unique in some ways. These waves are called ELECTROMAGNETIC (EM) WAVES. EM waves are different from mechanical waves in some important ways. EM waves are disturbance that transfers energy through a field. They can travel through medium but what makes them strange is that they can also transmit through empty space. Radiation is the term used to describe the transfer of energy in the form of EM wave. For a mechanical wave to travel, it must vibrate the medium as it moves. This makes use some of the waves’ energy. In the end, it makes them transfer all energy to the medium. As for EM waves, they can travel through empty space or vacuum so they do not give up their energy. This enables EM waves to cross great distances such as that from the sun to the Earth (which is almost vacuum) without losing much energy. In vacuum, EM waves travel at a constant speed of 300,000,000 meters per second (3.0 x 108 m/s). At this rate, the rays of the sun take 8 minutes to reach the Earth. Electromagnetic waves can also transmit with a material medium. They can also transfer energy to the medium itself. When they interact with matter, their energy can be converted into many different forms of energy. With these characteristics, electromagnetic waves are used for a wide variety of purposes. To show that EM waves characterize similar movement as that of the mechanical waves when they encounter a barrier, do the next activity. 9|Page Learning Task 2 On and Off! Objective: Prove that electromagnetic waves can be reflected. Materials TV with remote control Mirror with stand Procedure: 1. Turn on the TV on and off using the remote control. 2. Position the mirror at an angle with which could reflect the waves from the remote control to the TV. 3. Turn the TV on and off by aiming the remote control at the mirror. Guide Question 1. How would you position the remote control in order to turn the TV on and off? 2. What does this indicate? Properties of Electromagnetic Waves The wave shown in Figure 3, illustrates properties that are used to describe waves. A crest is the highest point of a wave. For an electromagnetic wave, this is the point in time when the field is strongest. A trough is the lowest point of a wave. For an EM wave, this is the point in time when the field is weakest. 10 | P a g e  Figure 3. Parts of a Wave Source:https://pa01000192.schoolwires.net/cms/lib/PA01000192/Centricity/Domain/13 5/Physics/PH%20Ch%2014/EandM%20Packet0001.pdf Different types of radiation are defined by their wavelengths, amplitude, and frequency. Wavelength is the distance between two identical points on successive waves. In most cases, wavelength is measured according to the distance between two successive wave crests or two successive troughs. A higher frequency causes a shorter wavelength and greater energy. Amplitude is a measure of the energy a wave carries. It is determined by measuring the distance from the midpoint of the wave to either a crest or a trough. Frequency is the number of wavelengths that pass by a certain point in a given time. A wave with high frequency generally has more energy than a wave with lower frequency. Frequency is expressed in Hertz (Hz). One hertz equals one cycle per second. Thus, Hertz can be expressed as “number of waves per second”. The higher the frequency, the closer the waves are together and the greater the energy carried by the waves will be. Learning Task 3. Below are the different terms to describe an electromagnetic wave and rearrange the jumbled letters to form the correct term being described. Do this on your answer sheet. 1. It is a disturbance in space. AVWE 2. It is the highest point in a wave. SECRT 3. It is the lowest point in a wave. THGOUR 4. It is the distance from the midpoint to the highest (or lowest) point of a wave. MUPLTDIAE 5. It is the distance between two successive identical parts of a wave ENETVWGHAL 6. It refers to the number of waves produced in one second. RYNEQFCEU 11 | P a g e The Electric and Magnetic Fields Together Accelerating electrons produce electromagnetic waves. These waves are a combination of electric and magnetic fields. A changing magnetic field produces an electric field and a changing electric field produces a magnetic field. As accelerated electrons produce an electric field of a wave, the varying electric field produces the wave’s magnetic field. Both the electric field and the magnetic field oscillate perpendicular to each other and to the direction of the propagating wave. Figure 4. Electromagnetic Wave https://in.pinterest.com/pin/346777240049 468014/ Speed of EM Wave All electromagnetic waves can travel through a medium but unlike other types of waves, they can also travel in vacuum. They travel in vacuum at a speed of 3x10 8 m/s and denoted as c, the speed of light. The wave speed, frequency and wavelength are related by the following equation: v = f where: v = wave speed or c (speed of light) expressed in meters per second (m/s) f = frequency expressed in Hertz (Hz)  = wavelength expressed in meters (m) Since all the electromagnetic waves (EM) have the same speed and that is equal to the speed of light, as wavelength increases, the frequency of the wave increases. Through the years, the advancement on the knowledge about electromagnetic waves led us to a modern technological world. Example Problems: (Assume that the waves propagate in a vacuum) 1. What is the frequency of a wave with wavelength of 20 m? Given: v=c=3 x 108 m/s  = 20 m Required: f = ? 12 | P a g e  Solution: From the original formula: v=c=f we will derive the formula for f which is f = c/ substituting the values f = 3 x 108 m/s 20 m f = 1.5 x 107 Hz 2. What is the frequency of EM waves with wavelength of 5 x 10-7 m? Given: v=c=3 x 108 m/s  = 5 x 10-7 m Required: f = ? Formula: v=c=f f=c/ f = 3 x 108 m/s 5 x 10-7 m f = 6 x 1014 Hz 3. Calculate the wavelength of radiation with a frequency of 610 kHz. ( Note: 1 kHz = 1000 Hz) Given: v=c=3 x 108 m/s f = 610 kHz x (1000 Hz/1 kHz) = 610,000 Hz Required:  = ? Formula: v=c=f =c/f  = 3 x 108 m/s 6.1 x 105 Hz  = 490 m Learning Task 4. Calculate the following problems. Show your solution in your answer sheet. 1. An electromagnetic wave that travels at a speed of 3.0 x 108 m/s in a vacuum and have a frequency of 1.5 x 1010 Hz. Calculate its wavelength. 2. What is the wavelength of a ray having a frequency of 4.80 x 1017 Hz? 3. An EM wave has a frequency of 6.01 x 1014 Hz. What is the wavelength? 13 | P a g e  What I Have Learned GENERALIZATION Now, let us sum up the concepts you have learned in this module. A wave is a disturbance that transfers energy. James Clerk Maxwell formulated the Electromagnetic Wave Theory which says that an oscillating electric current should be capable of radiating energy in the form of electromagnetic waves. Heinrich Hertz discovered the Hertzian waves which is now known as radio waves. Hertz is the unit used to measure the frequency of waves. Electromagnetic (EM) waves have unique properties. ► EM waves can travel through a vacuum. ► EM waves travel at the speed which is constant in a given medium and has a value of c = 3.0 x 108 m/s in vacuum. ► EM waves are disturbances in a field rather than in a medium. ► EM waves have an electric field that travels perpendicular with the magnetic field. ► EM waves form when moving charged particles transfer energy through a field. What I Can Do Answer the following. 1. How are frequency and wavelength of an electromagnetic wave related? 2. How are electromagnetic waves propagated? 3. An electromagnetic wave has a frequency of 9.95x107 Hz. What is its wavelength? 4. What is the frequency of a wave whose wavelength is 4.10 x 10-12 m? 14 | P a g e  5. Calculate the frequency of an electromagnetic wave that has the speed of 3.00 x 108 m/s and a wavelength of 2 mm. (1 mm = Assessment A. Multiple Choice. Choose the best answer. Write the letter on your answer sheet. 1. As the speed decreases, if we change the medium of electromagnetic waves from air to water, the frequency A. Also decreases C. Remains the same B. Also increases D. May increase or decrease 2. Which of the following is NOT true for electromagnetic waves? A. They can be reflected B. They transport energy C. They consist of changing electric and magnetic waves D. They travel at different speeds in vacuum, depending on their frequency 3. Electromagnetic waves travel A. With medium B. Without medium C. In a disturbed path D. With medium and without medium 4. Which statement best describes a proton that is being accelerated? A. It is attracted to other protons. B. It produces electromagnetic radiation. C. The magnitude of its charge increases. D. It absorbs a neutron to become an electron. 5. What is the speed of a EM wave in a vacuum? A. 0 m/s C. 3.00 x 108 m/s B. 1.13 x 10 m/s 3 D. 3.31 x 102 m/s 6. Who was this scientist famous of his theory of electromagnetism, which showed that light was electromagnetic radiation? A. Faraday B. Hertz C. Maxwell D. Oersted 7. A wave has a frequency of 5.0 x 10 hertz in a vacuum. What is the 14 wavelength of this wave? A. 1.5 x 1023 m C. 2.0 x 10-15 m B. 1.7 x 106 m D. 6.0 x 10-7 m 8. Electromagnetic waves are propagated through the interaction of A. Nuclear and electric fields B. Electric and magnetic fields C. Gravitational and electric fields D. Gravitational and magnetic fields 9. How much time does it take for an EM wave to reach a subject 6.0 meters across a room? A. 2.0 x 10-7 s C. 5.0 x 10-8 s B. 2.0 x 10-8 s D. 5.0 x 10-9 s 15 | P a g e  10. Which characteristic is the same for all types of EM waves traveling in a vacuum? A. Frequency B. Period C. Speed D. Wavelength 11. When an EM wave travels from one medium to another, what happens to its frequency? A. Increases B. Decreases C. Stays the same D. A & B 12. Who discovered the relationship between magnetism and electricity that serves as the foundation for the theory of electromagnetism? A. Andre Ampere C. Hans Christian Oersted B. Charles Coulomb D. Luigi Galvani 13. The distance between two crests or two troughs of a wave is called __________. A. Amplitude B. Frequency C. Hertz D. Wavelength 14. This scientist demonstrated the magnetic effect based on the direction of current. Who is this scientist? A. Faraday B. Hertz C. Maxwell D. Oersted 15. Which of the following is a TRUE statement about electromagnetic waves? A. People emit electromagnetic waves in the form of infrared energy B. A vibrating electric field is an example of an electromagnetic wave. C. Sound waves are electromagnetic waves with very low frequencies. D. The speed of an electromagnetic wave depends on its frequency and wavelength. Additional Activities To further understand the electromagnetic wave theory watch the video clips: 1. https://www.youtube.com/watch?v=FWCN_uI5ygY 2. https://www.youtube.com/watch?v=lTjSdnEcJV8 3. https://www.youtube.com/watch?v=fZnYE3kvhhA 16 | P a g e References and Links Printed Materials: Glencoe Physics Principles & Problems. The McGraw-Hill Companies, Inc., 2013 Kirkpatrick et. al. Physics: A World View, International Student Edition. The Tomson Corporation, 2007. Littell, McDougal. Science, Integrated Course 1, Teacher’s Edition. Evanston, Illinois: McDougal Littell, 2005. Padua, AL., Crisostomo RM., Practical and Explorational Physics Modular Approach. Vibal Publshing House, Inc., Copyright 2003 Yong, et al. Physics Insights, Low Price Edition. Jurong, Singapore: Pearson Education (Asia) Pte Ltd. Acosta, H., L. Alvarez, D. Angeles, R. Arre, MP. Carmona, A. Gatpo, et al. Science – Grade 10 Learner’s Material. Pasig City, Philippines: Rext Bookstore, Inc. and Department of Education, 2015. Hewitt, L., P. Hewitt, J. Suchocki. Conceptual Physical Science, Third Edition. Jurong, Singapore: Pearson Education South Asia PTE LTD, 2004. Electronic Sources: http://www.imaginationstationtoledo.org http://www.can- do.com/uci/ssi2001/emspectrum.html http://www.physicsclassroom.com/mmedia/waves/em.cfm http://science.hq.nasa.gov/kids/imagers/ems/ems2.html http://www.scienceinschool.org/2009/issue12/microwaves http://enviroadvocacy.com/measure-your-campaign/ http://sciencevault.net/11hscphys/82worldcommunicates/823%20em% 20waves.htm http://www.colorado.edu/ http://school.discoveryeducation.com/lessonplans/interact/ electromagneticspectrum.html https://www.thoughtco.com/electromagnetism-timeline-1992475 17 | P a g e https://pa01000192.schoolwires.net/cms/lib/PA01000192/Centricity/Do main/135/Physics/PH%20Ch%2014/EandM%20Packet0001.pdf Department of Education. “K to 12 Curriculum Guide Science (Grade 3 to 10)” Accessed October 2019 “https://www.deped.gov.ph/wpcontent/uploads/2019/01/Science- CG_with-tagged-sci-equipment_revised.pdf” LRMDS Portal. Science Modules. December 29, 2014. Accessed October 13, 2019. http://lrmds.deped.gov.ph/detail/6838 18 | P a g e  19 | P a g e WHAT I CAN DO 1. Frequency is determined by the amount of wavelength that pass in one second. Electromagnetic waves frequency emitted by an object increases as the temperature increases. The longer the wavelength the shorter the frequency. 2. The changing magnetic field, in turn, induces an electric field so that a series of electrical and magnetic oscillations combine to produce a formation that propagates as an electromagnetic wave.... At the same frequency, the magnetic field oscillates perpendicular to the electric field. 3. 0.301 m 4. 7.31 x 1019 Hz 5. 1.5 x 1011 Hz Learning Task 4 Learning Task 3 1. Wave 1. 2.0 x 10-2 m 2. Crest 3. Through 2. 6.3 x 10-10 m 4. Amplitude 3. 5.0 x 10-7 m 5. Wavelength 6. Frequency Learning Task 2. Learning Task 1 1. The remote control should be aimed at the mirror 1. c such that the incident beam strikes it at an angle 2. d that will direct the reflected beam towards the TV. 3. b 2. It indicates that EM waves can also be reflected just 4. a like mechanical waves. 5. e WHAT’S NEW Answers may vary WHAT’S IN A. 1. energy 2. crest 3. trough 4. wavelength 5. amplitude 6. frequency 7. hertz 8. longitudinal 9. sound 10. transverse B. 1. transverse 2. longitudinal PRETEST 1. d 2. a 3. a 4. a 5. a 6. a 7. b 8. b 9. d 10. d 11. d 12. c 13. b 14. a 15. d Answer Key