GRADE 10 SCIENCE SUBJECT QUARTER 1-4, Assignments of Earth science

Download GRADE 10 SCIENCE SUBJECT QUARTER 1-4 and more Assignments Earth science in PDF only on Docsity! MINDANAO MISSION ACADEMY The School that Offers Something Better Manticao, Misamis Oriental Adventist Education LEARNING MODULE FOR SCIENCE 10 Time Frame: Month of November NAME: Teacher: Reda B. Quidet Consultation schedule: Weekdays, Office Hours Degree: BSED General Science Contact number: 09099908399 Facebook account: Reda Babia Quidet Quarter 2: ELECTROMAGNETIC SPECTRUM LIGHT ELECTRICITY AND MAGNITISM Time Frame: 3" Module CONTENT STANDARD ™% The learners demonstrate an understanding of the different regions of the electromagnetic spectrum. * The learners demonstrate an understanding of the images formed by the different types of mirrors and lenses. ™% The learners demonstrate an understanding of the relationship between electricity and magnetism in electric motors and generators. PERFORMANCE STANDARD 4 The learner shall be able to use any form of media and present the effects of electromagnetic wave exposures to life and environment. ENDURING UNDERSTANDING 4 The effects of electromagnetic wave exposures to life and environment depend on the different regions of electromagnetic spectrum. ESSENTIAL QUESTIONS ™% How do electromagnetic wave exposures affect life and environment? TRANSFER GOAL ™% Students on their own and in the long run will be able to present the effects of electromagnetic wave exposure and make an informed decision to minimize the effects on life and environment using any form of media. LEARNING COMPETENCIES Compare the relative wavelengths of different forms of electromagnetic waves. Cite examples of practical applications of the different regions of EM waves, such as the use of radio waves in telecommunications. Explain the effects of EM radiation on living things and the environment. Predict the qualitative characteristics (orientation, type, and magnification) of images formed by plane and curved mirrors and lenses. Apply ray diagramming techniques in describing the characteristics and positions of images formed by lenses. Identify ways in which the properties of mirrors and lenses determine their use in optical instruments (e.g., cameras and binoculars). Demonstrate the generation of electricity by movement of a magnet through a coil. Explain the operation of a simple electric motor and generator. LEARNING TARGETS. | can state the different forms of EM spectrum | can explain what is electromagnetic spectrum. | can state the different forms of EM spectrum | can describe each region of EM spectrum. | can describe the speed of all waves in the EM spectrum. | can identify the differences of EM spectrum in terms of wavelengths and frequency | can distinguish which of the region is the most dangerous. | can describe the behavior of the different forms of EM spectrum. | can show the main idea and supporting details of the EM Spectrum. | can explain how EM wave behave. | can describe the relationship between wavelength and frequency. | can describe the EM wave Frequency | can describe the EM wave Wavelength | can distinguish which part of the EM spectrum a certain service include. | can identify services that harms human beings. | can identify services that human beings can benefit. | can identify which part of the EM spectrum each picture portray. | can explain the importance of EM spectrum to us. | can explain the harmful effect of EM spectrum to us. | can explain how GPS work. | can identify which wave GPS use. | can explain how microwaves work. | can explain the uses of microwaves. | can discover infrared and its effect. | can explain the relationship between frequency and the energy carried by an EM wave. | can block UV rays from the sun | can discover the effects of UV rays | can explain how x-ray work. | can explain the effects of x-ray to humans. | can explain the benefits of x-ray to humans. | can determine the height, width, and the distance from the mirror of the image formed by plane mirrors. | can compare the actual height, width and the distance from the mirror of the object with that of the image formed by plane mirror. fe FE FF FEF FEF EERE REEF ERR REE RE RRR EER ERE EEE RB Qyider Learning Module in Science 10 for Quarter 2.1 | can explain Specular/Regular Reflection. | can explain Diffuse/Irreg ular Reflection. | can compare the angle of reflection and the angle of incidence. | can state one of the laws of reflection | can compare the difference between concave and convex mirror. | can trace the four principal rays in curved mirrors. | can distinguish the features of a concave and a convex mirror | can construct ray diagrams to determine the location, orientation, size, and type of images formed by curved mirror. I can predict the exact orientation, type and magnification of image formed by the curved mirror. | can solve problems involving image formed in curved mirror. | can explain how glass is like a convex mirror. | can find the focal point. | can measure the focal length and linear magnification of a convex lens | can locate the image formed by convex mirror lens | can describe the image formed by a convex lens. I can trace the three most useful rays in concave and convex lens. | can construct ray diagrams for lenses. | can determine graphically the location, orientation, size and type of image formed. | can show graphically the changes in the image formed as an object's position is changed. | can predict the exact orientation, type and magnification of image formed by the curved lenses. | can solve problems involving image formed in curved lenses. | can construct a pin hole camera | can explain the factors that affect the image on the screen. | can construct a periscope and trace the incident and reflected rays. | can set up a simple microscope and investigate the factors affecting the magnification capabilities of a microscope. | can construct a simple telescope and investigate the factors affecting the magnification capabilities of a telescope. | can identify the basic recording equipment of a digital radio studio. | can classify whether devices use electricity and/or magnetism when used in recording audio. I can start a literature search on electromagnetic induction’s role in recording technology. | can identify the forces (attraction/repulsion) between two magnets and a magnet and magnetic/nonmagnetic materials. | can distinguish a magnet (permanent or temporary) from a non - magnetic object. | can induce magnetism in a magnetic material. | can infer the polarity of the magnetized object. | can identify the polarities and strengths of a bar magnet and magnetized objects using a compass. | can demonstrate magnetization by stroking. | can make an improvised electromagnet. | can explain electromagnetic induction | can recognize the contribution of Oersted, Ampere, and Faraday to the electromagnetic theory. | can explain electromagnetic induction | can recognize the contribution of Oersted, Ampere, and Faraday to the electromagnetic theory. | can explain the operation of a simple electric motor FREER RRR REE FREER FF FRE RRR RRR RRR EERE FRR ERE EE UNIT 2: LESSON 1. Electromagnetic Spectrum LESSON 2. Light LESSON 3. Electricity and Magnetism The moving iron core within the Earth acts like a giant bar magnet. It produces a weak geomagnetic field that surrounds and partially protects us from solar radiations. In like manner, the moving charges within the Sun generate an eruption of radiations. This produces a solar magnetic field that spreads throughout the solar system and beyond. Moreover, a solar wind of charged particles constantly interacts with the Earth’s changing geomagnetic field. In Grade 8 Science, you learned some characteristics of heat, visible light, and electricity whereas in Grade 9 Science, you were introduced to the forms and sources of energy. You also learned how electrical energy is generated, transmitted, and distributed. Using the principles of forces, motion and energy, Unit 2 of Grade 10 Science which is intended for the second quarter, supports investigations on the electric, magnetic and electromagnetic phenomena all around us. Eventually, this unit will help you to understand the different electromagnetic waves commonly known as the EM spectrum with a final emphasis on the visible light. A detailed study of the characteristics of the EM spectrum will help you appreciate the relevant applications and effects of some of the EM waves to us and our environment. Moreover, you will study the nature of light as it interacts with matter through reflection and refraction. There will be interesting activities on image formations using different mirrors and lenses. Lastly, you will be reacquainted with basic magnetism and its relationship with electricity by exploring electric and magnetic fields surrounding devices made up of magnets and current-carrying conductors. The chief goal of the activities in these modules is to acquaint you with the particular phenomenon in study, enable you to observe relationships between variables, help you to develop and communicate your tentative explanations of the phenomena or models, and lead you to further inquiry and deeper understanding. This module will help you learn the following competencies: Compare the relative wavelengths of different forms of electromagnetic waves. ™% Cite examples of practical applications of the different regions of EM waves, such as the use of radio waves in telecommunications. ™% Explain the effects of EM radiation on living things and the environment. ™% Predict the qualitative characteristics (orientation, type, and magnification) of images formed by plane and + # curved mirrors and lenses. Apply ray diagramming techniques in describing the characteristics and positions of images formed by lenses. Page 2 of 15 MINDANAO MISSION ACADEMY The School that offers Something Better IB Qyidet Learning Module in Science 10 for Quarter 2.1 Why are we here? Where do we come from? These are the most enduring of questions. It’s a story we wouldn't be able to tell without the one thing that connects us vividly to our vast cosmos: Light. Through light we can stare back across the entire history of the universe, and discover how it all began. Those ancient beams of light are messengers from the distant past. And they carry with them a story. The story of the origin of the universe. Gaze up into the night sky Capture the light And read the story of the universe Isn’t it a wonderful thing We are part of the universe Isn’t it a wonderful thing The story of the universe is our story Carried on waves of light Wave after wave after wave of light All the colors of the rainbow, colors of the rainbow Light can transport us to the past And we have become virtual time travelers Night falls, darker and darker And the universe fades into view Night falls, darker and darker Darker and darker Stars being born in distant realms Alien worlds created by gravity Stars that shine with the light of a thousand suns And vast swirling galaxies These waves of light are messengers from across the cosmos. And through them, we have discovered the wonders of our galaxy, frozen in time. Gaze up into the night sky Capture the light And read the story of the universe Isn’t it a wonderful thing We are part of the universe Isn’t it a wonderful thing The story of the universe is our story Carried on waves of light Wave after wave after wave of light All the colors of the rainbow, colors of the rainbow Billions and billions of suns Shining in the sky The story of the universe Carried on waves of light Gaze up into the night sky Capture the light And read the story of the universe ? Process Questions: BWNP Does the universe created light? Does the wave of light can tell us the real story of the universe? What causes the different colors of rainbow? What is the message of the song? ACTIVITY 2.2| PICK UP WORDS. Instruction: Listen again to the song “Waves of Light” and pick some words you think are essential for today’s lesson. Pick up at least ten (10) important words from the lyrics. Guess the given phrase below by filling up the missing letters. Write your answer on a separate sheet of paper. We are P of the U These W of L are M S that S with the L G up into the NS The S of the UisOS L can T us to the P B and B of SS in theS NF, DandD 1. 2. 3. 4. 5. 6. 7. 8. 2. 1 Process Questions: How does light travel? Those A B of Lare M from the D P 0. Through L we can S B across the E H of the U Do the phrases give you a hint of our topic? How important is light to us and to the universe as a whole? How can you infer the origins of light? INTEGRATION OF FAITH AND LEARNING: In science, a rainbow is an arch of colors formed in the sky in certain circumstances, caused by the 1 refraction and dispersion of the sun's light by rain or other water droplets in the atmosphere. However, sometime in the past a rainbow was used as a token of covenant between man and His God. According to the Scripture, explain when did the first rainbow appear and why was it created. Direct quotation from the MINDANAO MISSION ACADEMY The School that offers Something Better Page 5 of 15 RB Qyider Learning Module in Science 10 for Quarter 2.1 END OF EXPLORE In this level, your goal is to learn and understand the concepts about Electromagnetic wave (EM waves), electromagnetic spectrum, and examples of practical applications of the different regions of EM waves and explain the effect of EM radiation on living things and their environment. FIRM UP In your previous grade levels, you have learned that waves carry energy. You have also investigated the types of waves, its characteristics and propagation. How are the electromagnetic waves produced? What are the components of the different regions of the EM spectrum? Do EM waves bring harm to the environment? What are its negative effects? These questions will help you grasp the content of this lesson. Dh THINK BIG! ELECTROMAGNETIC SPECTRUM Can you imagine trying to take a photo with a radio? How about trying to tune in a radio station on your flashlight or heat your food with X-rays? Light, radio waves, and X-rays are all electromagnetic waves. But each has properties that make it more useful for some purposes and less useful for others. What makes light different from radio waves and X-rays? All electromagnetic waves travel at the same speed in a vacuum, but they have different wavelengths and different frequencies. Radiation in the wavelengths that your eyes can see is called visible light. But only a small portion of electromagnetic radiation is visible light. The rest of the wavelengths are invisible. Your radio detects radio waves, which have much longer wavelengths than visible light. X-rays, on the other hand, are waves with much shorter wavelengths than visible light. Recall how speed, wavelength, and frequency are related: Speed= Wavelength X frequency Because the speed of all electromagnetic waves is the same, as the wavelength decreases, the frequency increases. Waves with the longest wavelengths have the lowest frequencies. Waves with the shortest wavelengths have the highest frequencies. The amount of energy carried by an electromagnetic wave increases with frequency. The higher the frequency of a wave, the higher its energy. The electromagnetic spectrum is the complete range of electromagnetic waves placed in order of increasing frequency. The electromagnetic spectrum is made up of radio waves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays. The electromagnetic spectrum shows the range of different electromagnetic waves in order of increasing frequency and decreasing wavelength. Radio waves are the electromagnetic waves with the longest wavelengths and lowest frequencies. They include broadcast waves (for radio and television) and microwaves. Radio waves with longer wavelengths are used in broadcasting. They carry signals for both radio and television programs. A broadcast station sends out radio waves at certain frequencies. Your radio or TV antenna picks up the waves and converts the radio signal into an electrical signal. Inside your radio, the electrical signal is converted to sound. Inside your TV, the signal is converted to sound and pictures. The radio waves with the shortest wavelengths and the highest frequencies are microwaves. When you think of microwaves, you probably think of microwave ovens that cook and heat your food. But microwaves have many uses, including cellular phone communication and radar. Radar stands for radio detection and ranging. Radar is a system that uses reflected radio waves to detect objects and measure their distance and speed. To measure distance, a radar device sends out radio waves that reflect off an object. The time it takes for the reflected waves to return is used to calculate the object’s distance. To measure speed, a radar device uses the Doppler Effect. Because the car is moving, the frequency of the reflected waves is different from the frequency of the original waves. The difference in frequency is used to calculate the car’s speed. If you turn on a burner on an electric stove, you can feel it warm up before the heating element starts to glow. The invisible heat you feel is infrared radiation, or infrared rays. Infrared rays are electromagnetic waves with wavelengths shorter than those of radio waves. Heat Lamps Infrared rays has a higher frequency than radio waves, so they have more energy than radio waves. Because you can feel the energy of infrared rays as heat, these rays are often called heat rays. Heat lamps have bulbs that give off mostly infrared rays and very little visible light. These lamps are used to keep food warm at a cafeteria counter. Some people use heat lamps to warm up their bathrooms quickly. Most objects give off some infrared rays. Warmer objects give off infrared waves with more energy and higher frequencies than cooler objects. An infrared camera takes pictures using infrared rays instead of light. These pictures are called thermograms. A thermogram is an image that shows regions of different temperatures in different colors. You can use an infrared camera to see objects in the dark. Firefighters use infrared cameras to locate fire victims inside a dark or smoky building. Satellites in space use infrared cameras to study the growth of plants and the motions of clouds. Electromagnetic waves that you can see are called visible light. They make up only a small part of the electromagnetic spectrum. Visible light waves have shorter wavelengths and higher frequencies than infrared rays. Visible light waves with the longest wavelengths appear red in color. As the wavelengths decrease, you can see other colors of light. The shortest wavelengths of visible light appear violet in color. Visible light that appears white is actually a mixture of many colors. White light from the sun can be separated by a prism into the colors of the visible spectrum—red, orange, yellow, green, blue, and violet. Recall that when waves enter a new medium, the waves bend, or refract. The prism refracts different wavelengths of visible light by different amounts and thereby separates the colors. Red light waves refract the least. Violet light waves refract the most. Electromagnetic waves with wavelengths just shorter than those of visible light are called ultraviolet rays. Ultraviolet rays have higher frequencies than visible light, so they carry more energy. The energy of ultraviolet rays is great enough to damage or kill living cells. In fact, ultraviolet lamps are often used to kill bacteria on hospital equipment. Small doses of ultraviolet rays are useful. For example, ultraviolet rays cause skin cells to produce vitamin D, which is needed for healthy bones and teeth. However, too much exposure to ultraviolet rays is dangerous. Page 6 of 15 MINDANAO MISSION ACADEMY The School that offers Something Better RB Qyider Learning Module in Science 10 for Quarter 2.1 Ultraviolet rays can burn your skin, cause skin cancer, and damage your eyes. If you apply sunblock and wear sunglasses that block ultraviolet rays, you can limit the damage caused by ultraviolet rays. X-rays are electromagnetic waves with wavelengths just shorter than those of ultraviolet rays. Their frequencies are just a little higher than ultraviolet rays. Because of their high frequencies, X-rays carry more energy than ultraviolet rays and can penetrate most matter. But dense matter, such as bone or lead, absorbs X-rays and does not allow them to pass through. Therefore, Xrays are used to make images of bones inside the body or of teeth. X-rays pass through skin and soft tissues, causing the photographic film in the X-ray machine to darken when it is developed. The bones, which absorb X-rays, appear as the lighter areas on the film. Too much exposure to X-rays can cause cancer. If you've ever had a dental X-ray, you'll remember that the dentist gave youa lead apron to wear during the procedure. The lead absorbs X-rays and prevents them from reaching your body. X-rays are sometimes used in industry and engineering. For example, to find out if a steel or concrete structure has tiny cracks, engineers can take an X-ray image of the structure. X-rays will pass through tiny cracks that are invisible to the human eye. Dark areas on the X-ray film show the cracks. This technology is often used to check the quality of joints in oil and gas pipelines. Gamma rays are the electromagnetic waves with the shortest wavelengths and highest frequencies. Because they have the greatest amount of energy, gamma rays are the most penetrating of all the electromagnetic waves. Some radioactive substances and certain nuclear reactions produce gamma rays. Because of their great penetrating ability, gamma rays have some medical uses. For example, gamma rays can be used to kill cancer cells inside the body. To examine the body’s internal structures, a patient can be injected with a fluid that emits gamma rays. Then a gamma ray detector can form an image of the inside of the body. Some objects in space give off bursts of gamma rays. The gamma rays are blocked by Earth’s atmosphere, so gamma ray telescopes that detect them must orbit above Earth’s atmosphere. Astronomers think that explosions of stars in distant galaxies are one way of producing these gamma rays. Taken from: http://grove.ccsd59.org/wp-content/uploads/sites/10/2015/05/Waves-of-the-Electromagnetic-Spectrum.pdf ACTIVITY 2.3 | CONCEPT WHEEL WITH 7 SPOKES Learning Competencies: & Compare the relative wavelength of different forms of electromagnetic waves. Learning Targets: *%& can describe each region of EM spectrum. %& =| can distinguish which of the region is the most dangerous. *% can describe the behavior of the different forms of EM spectrum. Instruction: After reading, accomplish the Concept Wheel with 7 Spokes graphic organizer. Write the different forms of electromagnetic waves within each spoke with its short description. Use the box for additional information or ideas. Submit your work. * 4 Process Questions: 1. How do the regions of the EM spectrum differ from each other? 2. Which of the regions do you think is the most dangerous regions? Why? 3. Which of the regions is very hard to control? Why? ACTIVITY 2.4 | CONNECT THEM ALL Learning Competencies: & Compare the relative wavelength of different forms of electromagnetic waves. Learning Targets: %& | can describe each region of EM spectrum. & | can show the main idea and supporting details of the EM Spectrum. Instruction: Using the Main Idea and Supporting Details Organizer, summarize your readings about Electromagnetic Spectrum. Fill out the boxes showing the main idea and the supporting details of the Electromagnetic Spectrum. Activity 2.5 | VIDEO ANALYSIS NOTE! If internet connection is unavailable the transcribe file of the videos are given below. Learning Competencies: %& Compare the relative wavelength of different forms of electromagnetic waves. Learning Targets: + Ican describe each region of EM spectrum. + Ican explain how EM wave behave. Page 7 of 15 MINDANAO MISSION ACADEMY The School that offers Something Better RB Qyider Learning Module in Science 10 for Quarter 2.1 ACTIVITY 2.8 | IDENTIFICATION LEARNING COMPETENCIES: % Explain the effects of EM radiation on living things and the environment. Learning Targets: ™% | can identify which part of the EM spectrum each picture portray. ™% | can explain the importance of EM spectrum to us. % | can explain the harmful effect of EM spectrum to us. Instruction: Identify the objects below if it is an example of radio wave, microwave, infrared, visible light, ultraviolet rays, x- rays, and gamma rays and answer the process questions. Answer the table found in your answer sheet. Process Questions: 1. How important EM spectrum to you? 2. Do they give conveniences to our lives? 3. Do they bring harm to the environment? How? ACTIVITY 2.9 | GPS AT WORK (CLOSE READING) LEARNING COMPETENCIES: ™% Cite examples of the different regions of EM waves, such as the use of radio waves in telecommunications. Learning Targets: & | can explain how GPS work. %& | can identify which wave GPS use. Instruction: You will be reading an article about GPS and how does it work. Use any color highlighter for highlighting information that you think important for you to answer the process question. GLOBAL POSITIONING SYSTEM (GPS) Global Positioning System (GPS) is a worldwide radio-navigation system formed from the constellation of 24 satellites and their ground stations. The Global Positioning System is mainly funded and controlled by the U.S Department of Defense (DOD). The system was initially designed for the operation of U. S. military. But today, there are also many civil users of GPS across the whole world. The civil users are allowed to use the Standard Positioning Service without any kind of charge or restrictions. Global Positioning System tracking is a method of working out exactly where something is. A GPS tracking system, for example, may be placed in a vehicle, on a cell phone, or on special GPS devices, which can either be a fixed or portable unit. GPS works by providing information on exact location. It can also track the movement of a vehicle or person. So, for example, a GPS tracking system can be used by a company to monitor the route and progress of a delivery truck, and by parents to check on the location of their child, or even to monitor high-valued assets in transit. A GPS tracking system uses the Global Navigation Satellite System (GNSS) network. This network incorporates a range of satellites that use microwave signals that are transmitted to GPS devices to give information on location, vehicle speed, time and direction. So, a GPS tracking system can potentially give both real-time and historic navigation data on any kind of journey. GPS provides special satellite signals, which are processed by a receiver. These GPS receivers not only track the exact location but can also compute velocity and time. The positions can even be computed in three-dimensional views with the help of four GPS satellite signals. The Space Segment of the Global Positioning System consists of 27 Earth-orbiting GPS satellites. There are 24 operational and 3 extra (in case one fails) satellites that move round the Earth each 12 hours and send radio signals from space that are received by the GPS receiver. The control of the Positioning System consists of different tracking stations that are located across the globe. These monitoring stations help in tracking signals from the GPS satellites that are continuously orbiting the earth. Space vehicles transmit microwave carrier signals. The users of Global Positioning Systems have GPS receivers that convert these satellite signals so that one can estimate the actual position, velocity and time. The operation of the system is based on a simple mathematical principle called trilateration. Trilateration falls into two categories: 2-D Trilateration and 3-D Trilateration. In order to make the simple mathematical calculation the GPS receiver must know two things. First it must know the location of the place is to be traced by at least three satellites above the place. Second, it must know the distance between the place and each of those Space Vehicles. Units that have multiple receivers that pick up signals from several GPS satellites at a same time. These radio waves are electromagnetic energy that travels at the speed of light. A GPS tracking system can work in various ways. From a commercial perspective, GPS devices are generally used to record the position of vehicles as they make their journeys. Some systems will store the data within the GPS tracking system itself (known as passive tracking) and some send the information to a centralized database or system via a modem within the GPS system unit on a regular basis (known as active tracking) or 2-Way GPS. A passive GPS tracking system will monitor location and will store its data on journeys based on certain types of events. So, for example, this kind of GPS system may log data such as where the device has traveled in the past 12 hours. The data stored on this kind of GPS tracking system is usually stored in internal memory or on a memory card, which can then be downloaded to a computer at a later date for analysis. In some cases the data can be sent automatically for wireless download at predetermined points/times or can be requested at specific points during the journey. Page 10 of 15 MINDANAO MISSION ACADEMY The School that offers Something Better RB Qyider Learning Module in Science 10 for Quarter 2.1 An active GPS tracking system is also known as a real-time system as this method automatically sends the information on the GPS system to a central tracking portal or system in real-time as it happens. This kind of system is usually a better option for commercial purposes such as fleet tracking or monitoring of people, such as children or elderly, as it allows a caregiver to know exactly where loved ones are, whether they are on time and whether they are where they are supposed to be during a journey. This is also a useful way of monitoring the behavior of employees as they carry out their work and of streamlining internal processes and procedures for delivery fleets. & Process Questions: 1. How does a GPS work? 2. What was the purpose why GPS was created? 3. Which wave of the EM Spectrum GPS use? 4. How does this wave use in GPS? Taken from: http://www.eetimes.com/document.asp?doc_id=1278363 http://www. ener-chi.com/the-harmful-side-effects-of-x-rays-often-pose-a-greater-risk-than-the-original-health-problem/ Activity 2.10 | Microwaves Turn On (Article Analysis) LEARNING COMPETENCIES: + Cite examples of the different regions of EM waves, such as the use of radio waves in telecommunications. Learning Targets: + can explain how microwaves work. + Ican explain the uses of microwaves. Microwaves have smaller wavelengths than radio waves. They are used in satellite communications, radar, television transmission and cooking. APPLICATIONS OF MICROWAVES Satellite Communications Microwaves can penetrate the atmosphere of the earth. This is the reason why they are used for satellite communications. Communication satellites travel around the earth at an altitude of 35, 000 km above the equator. They move at a speed of 11 300 km/h and revolve around the earth every 24 hours, the same rate as the rotation of the earth. This makes them appear to be stationary when seen on Earth. Antennae are mounted to point in fixed directions towards these satellites. Microwaves signals are transmitted by an antenna to a satellite which amplifies and re-transmits the signal to an antenna in other parts of the world. This is how we communicate with the rest of the world. Radar Microwaves have short wavelengths and are reflected by small objects. This property is used in radars. Radar is the acronym of radio detection and ranging. A radar system is consists of an antenna, transmitter, and a receiver. The antenna whirls around continuously to scan the surrounding area. The transmitter sends out a narrow beam of microwaves in short pulses. A distant object reflects some of the signal back to the receiver. The direction to which the signal was received gives the direction of the object. The distance of the object can be calculated from the time lag between the transmitted pulse and the reflected pulse. Terrestrial Communication Microwaves are used to transmit television news coverage from mobile broadcast vehicles back to the station. The news crew can also set up a small antenna to send signals to a communication satellite. This is how news are broadcasted and watched live around the world. A cell phone is a radio transmitter and receiver that uses microwaves. Cellular phones depend on overlapping network of cells or areas of land several kilometres in diameter. Each cell has its tower that receives and sends microwave signals. The figure below will give you further understanding on the process. Microwave oven In a microwave oven, foods absorb certain microwave frequencies very strongly. The microwaves penetrate the food being heated. It will agitate the water molecules within the food, thus creating molecular friction which then produces heat that will cook it. 2 Process Questions: Why microwave use for telecomm unication? Why RADAR is important? How does radar use? Does RADAR uses harmful EM wave? Do microwaves give negative effects to the environment? RYN ACTIVITY 2.11 | A TIME TO LISTEN Page 11 of 15 MINDANAO MISSION ACADEMY The School that offers Something Better RB Qyider Learning Module in Science 10 for Quarter 2.1 LEARNING COMPETENCIES: 4 Explain the effects of EM radiation on living things and the environment. Learning Targets: %& | can discover infrared and its effect. ™ | can explain the relationship between frequency and the energy carried by an EM wave. Instruction: This time the teacher will give information for you to gain more knowledge about the EM spectrum. Take time to take down notes and ask questions to acquire knowledge. INFRARED Infrared radiation lies beyond the red end of the visible light. It is emitted by all objects. The amount and wavelength of radiation depend on temperature. Below 5000C, an object emits only infrared radiation. Above 500°C, an object glows and emits both infrared and some visible light. Our bodies radiate infrared and under infrared camera or a night vision goggle, our images appear in variety of colors. The differences in color determine the differences in temperature. For example, shades of blue and green indicate regions of colder temperature; and red and yellow indicate warmer temperature. The dog is covered with thick coat of fur that prevents the heat generated by the dog’s body from escaping. Notice that the dog’s nose is cold while the eyes and mouth areas are warm. The following are some useful applications of IR radiation: 1. Infrared photographs taken from a satellite with special films provide useful details of the vegetation on the Earth's surface. 2. Infrared scanners are used to show the temperature variation of the body. This can be used for medical diagnosis. 3. Infrared remote controls are used in TVs, video, cassette recorders, and other electronic appliances. 4. Some night-vision goggles use IR. 5. Some autofocus cameras have transmitter that sends out infrared pulses. The pulses are reflected by the object to be photographed back to the camera. The distance of the object is calculated by the time lag between the sending and receiving of pulses. The lens is then driven by a built-in motor to adjust to get the correct focus of the object. 2 Process Question: 1. How infrared is being use? 2. What are the colors indicate? 3. Is infrared wave harmful to human? Why? 4. What are the useful application of infrared radiation? THE VISIBLE SPECTRUM When white light passes through a prism, it is separated into its constituent colors: the red, orange, yellow, green, blue, indigo and violet. These colors do not distinctly separate but they continuously change from red to violet. Red color has the longest wavelength from among these colors and violet has the shortest. Our eyes are sensitive to electromagnetic waves of wavelengths that ranges from 4x10-7 m to 7x10-7 m. This is the range of wavelengths of white light. Thus, the spectrum of white light is therefore called the visible spectrum. Table 3 shows the wavelengths of the different colors that constitute the white light. Color Wavelength (nm) Violet-Indigo 390 to 455 Blue 445 to 492 Green 492 to 577 Yellow 577 to 597 Orange 597 to 622 Red 622 to 700 ULTRAVIOLET RADIATION Ultraviolet radiation lies just beyond the violet end of the visible spectrum. Ultraviolet waves have shorter wavelengths than the visible light and carry more energy. SOME USES OF UV RADIATION The sun is our main source of ultraviolet radiation but there are also artificial sources of UV light. Ultraviolet radiation in UV lamps are used by banks to check the signature on a passbook. The signature is marked on the passbook with fluorescent ink. It becomes visible when viewed under an ultraviolet lamp. These lamps are also used to identify fake banknotes. Ultraviolet radiation is also used in sterilizing water from drinking fountains. Some washing powder also contains fluorescent chemicals which glow in sunlight. This makes your shirt look whiter than white in daylight. Ultraviolet radiation in sunlight produces vitamin D in the skin and gives us tanning effect. But since UV rays have high energy, it could be harmful to some extent. It could burn the skin and hurt our eyes. Overexposure to UV radiation may cause skin cancer. Suntan or sunscreen lotions serve as filters to protect the body from ultraviolet radiation. Page 12 of 15 MINDANAO MISSION ACADEMY The School that offers Something Better