Training of Trainers for Grade 10 of the K to 12 Enhanced Basic Education Program April 27 – May 2, 2015 (Luzon Cluster)

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Module 2ELECTROMAGNETIC SPECTRUMTraining of Trainers for Grade 10 of the K to 12 Enhanced Basic Education ProgramApril 27 May 2, 2015 (Luzon Cluster)

1Spiraling of conceptsModule 2 CompetenciesModule 2 activitiesActivity 2: Now you go! Now you wont!DiscussionEssential Characteristics of Science Inquiry

Outline of PresentationSession Guide2In Grade 7

EM spectrum consists of various types of waves.The higher the frequency, the shorter the wavelength.High energy EM waves have high frequency and short wavelengths.In Grade 7, students learned that: EM spectrum consists of various types of waves. Relationship between frequency and wavelength The higher the frequency, the shorter the wavelength (and vice versa). High energy electromagnetic waves have high frequency and short wavelengths.3In Grade 8

visible lightLight is composed of different colors.The arrangement of colors of light shows the hierarchy of the colors corresponding energy.In Grade 8 the focus is on the visible light. As the name implies, the only visible EM waves to us. Light is composed of different colors. The arrangement of colors of light shows the hierarchy of the colors corresponding energy. The red light has the least energy and blue light has the most energy. Violet light bends more than red light when dispersed.

4In Grade 10Applications of the different EM waves

Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.htmlIn Grade 10, the focus is on applications of different EM waves e.g. communication, medical, etc5TRUE OR FALSE:Electromagnetic waves carry energy.An electromagnetic wave is a longitudinal wave.Electromagnetic waves can travel in an empty space.4. Sound waves are electromagnetic waves.5. Different colors of light have the same amount of energy.Sample Pre-assessmentThis can be a review questions for students.6The learners should be able to:compare the relative wavelengths of different forms of electromagnetic radiation explain uses of the different forms of EM radiation create models on how materials react to EM radiation other than light (e.g. glass is opaque to some UV rays) explain the effects of EM radiation to living things

Competencies7How it came about [Contribution of different scientist]Now you go! Now you wont! [Materials that allow/block EM waves]Sound check[Producing and detecting radio waves]Then there was sound [Parts of a radio transmitter and receiver]Its getting hotter [About infrared radiation]Screen the UV out [About UV radiation]

Activities in Module 2Hey Hans, the opposite could be true! A changing magnetic field produces an electric field. Hans Christian Oersted1777-1851

James Clerk Maxwell1831-1879OMG! The compass needle move near the current-carrying wire. This shows electric current creates magnetic field.Activity 1: How it came abouthttp://www.rare-earth-magnets.com/hans-christian-oersted/

You both got it right! An electromagnetic wave exists when the changing magnetic field causes a changing electric field, which then causes another changing magnetic field, and so on.

Heinrich Hertz1857-1894http://en.wikipedia.org/wiki/Heinrich_Hertzhttp://simple.wikipedia.org/wiki/Michael_FaradayMichael Faraday1791-1867

http://soulconnection.net/glossary_in_depth/maxwell.htmlYou got it right Maxwell. I proved the existence of EM waves!Image credit:Activity 1discusses the contribution of different scientists in the development of electromagnetic wave theory.The students are asked to make a concept web or comic strips of the contributions of the following scientist: Ampere, Faraday, Hertz, Maxwell, and Oersted.This is just a sample.9Electromagnetic wavesA moving charge creates magnetic field.

A changing magnetic field causes a changing electric field.

Image credit:http://www.school-for-champions.com/science/magnetic_field_moving_charges.htm#.VThZiyaKCM8

Image credit:http://electrical4u.com/faraday-law-of-electromagnetic-induction/10Electromagnetic waves

The successive production of electric and magnetic field results to the creation EM wave.An EM wave propagates outward from the source.Image credit:http://www.astronomynotes.com/light/s2.htm11James Clerk Maxwell (lived 1831--1879) put these ideas together and proposed that if a changing magnetic field can make an electric field, then a changing electric field (from an oscillating electric charge, for example) should make a magnetic field. A consequence of this is that changing electric and magnetic fields should trigger each other and these changing fields should move at a speed equal to the speed of light. To conclude this line of reasoning, Maxwell said that light is an electromagnetic wave. Later experiments confirmed Maxwells's theory.Electromagnetic waves

The electric and magnetic fields vibrate at right angles to the direction the wave travels so it is a transverse wave.Image credit:http://www.astronomynotes.com/light/s2.htm12

Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html

Newton set up a prism near his window, and projected a beautiful spectrum 22 feet onto the far wall. Further, to prove that the prism was not coloring the light, he refracted the light back together.Image credit:http://www.webexhibits.org/colorart/bh.htmlThe modern understanding of light and color begins with Isaac Newton.The discovery of the different types of EM waves.13

Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html

Image credit:http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/discovery.htmlFrederick William Herschel (1738 - 1822)In 1800 he performed a famous experiment where he tried to measure the temperature of different colours of the spectrum by placing a thermometer on each colour. He found to his amazement that the hottest part of the spectrum was in a place where there was no colour at all. It was a spot beyond the red end of the spectrum. For the first time it was possible to talk about invisible light. This hot light became known as Infra Red (below the red) because it was shown to have longer wavelength than visible light. [http://www.krysstal.com/spectrum.html]

Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.htmlJohann Wilhelm Ritter (1776 - 1810)

Image credit:http://coolcosmos.ipac.caltech.edu/cosmic_classroom/classroom_activities/ritter_bio.htmlIn chemistry at that time there was a rumour that blue light was more efficient at initiating chemical change than red light. Ritter tried to measure the speed at which silver chloride broke down with different colours. He proved that blue light was indeed more efficient that red light. He was amazed, however, that the most vigorous reactions took place in the region beyond the violet where nothing could be seen.This new radiation was originally called Chemical Rays but is now called Ultra Violet (beyond the violet). Ultra Violet differs from visible light only in its wavelength which is shorter. [http://www.krysstal.com/spectrum.html]

Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.htmlHeinrich Rudolf Hertz (1857 - 1894)

Image credit:http://en.wikipedia.org/wiki/Heinrich_HertzHe set up electric circuits that produced oscillations and managed to produce electromagnetic radiation with a wavelength of 66cm (over a million times longer than light). This radiation could be picked up by other circuits set up quite a distance away. The new radiation was first called Hertzian Waves; this became Radiotelegraphic Waves after Marconi. We now call them Radio Waves. [http://www.krysstal.com/spectrum.html]

Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.htmlPerry Spencer (1894 - 1970) invented the microwave ovenIn 1945, Percy Spencer was experimenting with a new vacuum tube called a magnetron while doing research for the Raytheon Corporation. He was intrigued when the candy bar in his pocket began to melt, so he tried another experiment with popcorn. When it began to pop, Spencer immediately saw the potential in this revolutionary process. In 1947, Raytheon built the first microwave oven, the Radarange.[http://science.howstuffworks.com/innovation/scientific-experiments/9-things-invented-or-discovered-by-accident2.htm]The scientists discovered the cosmic microwave background radiation. This radiation, which fills the entire Universe, is believed to be a clue to it's beginning, something known as the Big Bang. Arno Penzias and Robert Wilson

Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.htmlWilhelm Conrad Roentgen (1845 - 1923)On the night of 5 November 1895, he noticed a glow coming from a chemical called barium platinocyanide. This chemical glowed whenever the tube was on, even if he put cardboard between it and the tube. Roentgen went on to show that the glow was caused by a highly penetrating but invisible radiation given off by the tube. It passed through paper, thin sheets of metal, flesh. It could ionise gases and had wave properties like light but only much shorter wavelengths. The new radiation was called X-Rays because of their mysterious properties. Roentgen refused to patent the discovery or make any financial gain out of it but he was awarded the first ever Nobel Prize for Physics. [http://www.krysstal.com/spectrum.html]

Image credit:http://www.two-views.com/article_Rontgen.html

Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.htmlVillard discovered gamma radiation in 1900, while studying radiation emitted from radium. Villard knew that his described radiation was more powerful than previously described types of rays from radium, which included beta rays, first noted as "radioactivity" by Henri Becquerel in 1896, and alpha rays, discovered as a less penetrating form of radiation by Rutherford, in 1899. However, Villard did not consider naming them as a different fundamental type. Villard's radiation was recognized as being of a type fundamentally different from previously named rays, by Ernest Rutherford, who in 1903 named Villard's rays "gamma rays" by analogy with the beta and alpha rays that Rutherford had differentiated in 1899.[http://en.wikipedia.org/wiki/Gamma_ray]Paul Ulrich Villard(1860 - 1934)Image credit:http://en.wikipedia.org/wiki/Paul_Ulrich_Villard

EM spectrum is a continuum of EM waves arranged according to frequency and wavelength.It shows a gradual progression from the waves of lowest frequency to the waves of highest frequency or vice versa.The different EM waves do not have exact dividing region.20Module 2: Electromagnetic SpectrumMotivation: Call me maybeHey I just met youAnd this is crazyBut here's my number So call me maybe(insert number here)

Cell phones uses microwaves to transmit and receive information.Remote control of RC cars also sends a control signal using radio waves.

22Now you go!Now you wont!Activity 2Deals with the characteristics of EM waves.23Identify materials that can block or allow radio waves.Compare the speed of the car when the transmitter is without cover and when it is covered with different materials.Objectives24Questions to be investigatedWhat materials allow radio waves to pass through them? What materials block radio waves? Materials

aluminum foiltransparent plasticcolored paperwax paperkitchen paper towelLatex glovesRemote- controlled carPlease handle the materials carefully.Do not drop the remote control or the car.26

Procedure2Wrap the antenna around the remote control. Secure it with a twist-tie wire or rubber band.

1Test the RC car if it is working.27Procedure3Use the remote control to make the toy car run. [The car should run in a straight path. If not, place the car between two planks of wood or meter sticks.]Image of car:http://www.dreamstime.com/royalty-free-stock-photo-red-german-expensive-car-collectible-toy-cabriolet-isolated-white-background-image40543185

Procedure4Choose a distance for the car to travel on. Use a stopwatch (cell phone) to get the time it took the car to travel the distance. Maintain the distance between the car and the remote control. Press once the forward button and dont release it until the car reached the finish line of the distance you set.Procedure5Start measuring the time it took the car to cover the distance you set with the remote control without cover first. Record the time in Table 1.6Wrap the remote control one at a time with the different materials. Make sure that it is completely covered.

Make sure you know where the forward button is. Materials to test:The materials should be of the same size so the remote control will be wrapped with equal thickness.The materials will be used by other group. Please unfold them carefully after each use.

It is important for an experiment to be a fair test. You conduct a fair test by making sure that you change one factor at a time while keeping all other conditions the same. Conducting a fair test is one of the most important ingredients of doing good, scientifically valuable experiments. To insure that your experiment is a fair test, you must change only one factor at a time while keeping all other conditions the same. In the materials, the latex glove is of different size from the other materials because a rubber that can be cut similar to the other materials is not available.32Procedure7Record in Table 1 the time it took the car to cover the distance you set with the remote control covered with different materials.Material covering the remote controlRC car time oftravel (s)ObservationsNo coverColored PaperWax PaperKitchen paper towelTransparent PlasticAluminum FoilLatex glovesTable 134Which of the materials that cover the remote control allows the radio waves to pass through? What evidence shows radio waves pass through these materials?Which of the materials that cover the remote control blocks the radio waves? What evidence shows radio waves was blocked by these materials?What kind of materials allowed radio waves to pass through?What kind of materials blocked radio waves?What do the results of the activity tell about the characteristics of radio waves?Compare the time taken by the car to travel the distance you set when the remote control was not covered to the time when the remote control was covered with different materials. Are they the same? What does this tell about the strength of the signal sent by the remote control when it hits the material covering it?

Guide Questions:351. Which of the materials that cover the remote control allows the radio waves to pass through? What evidence shows radio waves pass through these materials?

2. Which of the materials that cover the remote control blocks the radio waves? What evidence shows radio waves was blocked by these materials?

Guide Questions:aluminum foiltransparent plasticcolored paperwax paperkitchen paper towelLatex glovesThe RC car moved. The RC car did not move.363. What kind of materials allowed EM waves to pass through?

4. What kind of materials blocked EM waves?

Guide Questions:Paper (cellulose)colored paperwax paperkitchen paper towelRubber (elastomers)Latex glovesPlastic (polyethylene) transparent plasticAluminum - Metallicaluminum foil5. What does the result of the activity tells about the characteristic of radio waves?

6. Compare the time taken by the car to travel the distance you set when the remote control was not covered to the time when the remote control was covered with different materials. Are they the same? What does this tell about the strength of the signal sent by the remote control when it hits the material covering it?

Radio waves can be blocked by some materials.Radio waves can pass through some materials.NoThe signal can be weakened by the material covering the remote control.Guide Questions:Discussion

radiowavestransmitting antennareceiving antenna (not visible outside the car)

receiving antenna Receiver - An antenna and circuit board inside the toy receives signals from the transmitter and activates motors inside the toy as commanded by the transmitter.Transmittersends a control signal to the receiver using radio waves The remote control send something to the car that makes the car move.This something is a signal which is an EM wave called radiowaves.The remote control which is the transmitter transmit radiowaves at a certain frequency.Located inside the car is the receiver. Part of the receiver is the antenna that receives the signal. It is not visible outside the car used in the activity. But if you open the car, you can see the antenna attached on the car.

39Discussion

Transmitter:sends a control signal to the receiver using radio waves

Power supply: Provides the necessary electrical power to operate the transmitter.

Transmitter consists of several elements that work together to generate radio waves that contain useful information Three things happen to EM waves when it encounters a barrier. It can bounce (reflectance or scattering), pass through (transmittance), or just plain stop (absorbance).

DiscussionImage credit:https://sites.google.com/site/waveslightandsoundunit/03---unit-lessons/04---light-wavesWhen a radio wave reaches an obstacle, some of its energy is absorbed and converted into another kind of energy, while another part is attenuated and continues to propagate, and another part may be reflected. DiscussionAttenuation is when a signal's power is reduced as it is being transmitted.Attenuation increases with a rise in frequency or in distance. Also, when a signal collides with an obstacle, the level of attenuation depends strongly on which type of material the obstacle is made of.What is Attenuation Coefficient?The attenuation coefficient is the level by which a material will block or interfere with radio waves. This coefficient depends heavily on the thickness and composition of the material. Cardboard, paper, many plastics, water, and glass are all substances with very low attenuation coefficients. In addition, wood, brick, and cement have a limited effect on making radio waves blocked. However, metallic compounds, steel-reinforced concrete and the Earth reflect signals, preventing radio signals from passing through.DiscussionProperties of mediaThe weakening of signal strength is largely due to the properties of the medium that the wave is passing through. Here is a table showing attenuation levels for different materials:

MaterialsDegree of AttenuationExamplesMaterialsDegree of AttenuationExamplesairnoneOpen spacebricksmediumwallswoodlowDoor , floor, partitionplastermediumpartitionsplasticlowpartitionpaperhighRolls of paperglasslowUntinted windowsconcretehighLoad-bearing walls, floorsTinted glassmediumTinted windowsBullet proof glasshighBullet proof windowswatermediumaquariummetalVery highMetal cabinet, elevator cageLiving creaturesmediumCrowds, animals, people, plantsSource:http://en.kioskea.net/contents/832-propagation-of-radio-waves-802-11442 Types of matter (substance) that affect Radio wavesConductorsCopperAluminumSilverGoldInsulators(Dielectrics)PaperPlasticTeflonGlassCeramicDry woodAs the radio wave travels through the dielectric material some of the energy is absorbed generating heat and some of the radio waves travel through and comes out of the other side.

If the material is metal, almost all of the radio waves are reflected within the first few atoms of the material. A small amount of energy is absorbed by the silver atoms and converted to heat.

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Students can take the investigation further by comparing the ability of the same materials in blocking other EM Waves .Extension Activity

Ionizing radiationNon-ionizing radiationStudents can perform the extension activity for microwaves using cellphone, infrared using TV remote control, and visible light. Non-ionizing radiation is typically safe. It causes some heating effect, but usually not enough to cause any type of long-term damage to tissue. Radio waves, visible light and microwave radiation are considered non-ionizing.For ionizing radiation, the students can do research on what materials block UV, X-ray and gamma radiation.This type of radiation contains enough electromagnetic energy to strip atoms and molecules from the tissue and alter chemical reactions in the body. Thus, students cannot perform activities with ionizing radiation but instead do research on what materials can block them.46

Students can take the investigation further by controlling variables such as the thickness of materials.

Extension ActivityCharacteristicsActivity 2: Now you go! Now you wont!Engaging in scientifically-oriented questionsGathering evidence5 Essential Characteristics of Scientific InquiryWhat materials allow/block radio waves?Observe the car if it moves or notInfer that if the car moves, then the radio waves emitted by the transmitter pass through the material covering itInfer that if the car did not move, then the radio waves emitted by the transmitter did not pass through the material covering it5 Essential characteristics of scientific inquiry48CharacteristicsActivityProviding explanations based on evidence and scientific knowledgeEvaluating explanationsJustifying and communicating explanations5 Essential Characteristics of Scientific InquiryIf the material blocking the radio wave is metal, almost all of the EM waves are reflected. If the material blocking the EM wave is dielectric, some of the EM waves are absorbed and some are transmitted. Thank you!