g10_ntot_physics_electromagnetic_spectrum.pptx

Physics

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

2. Spiraling of concepts Module 2 Competencies Module 2 activities Activity 2: Now you go! Now you won’t! Discussion Essential Characteristics of Science Inquiry Outline of Presentation

3. In 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.

4. In Grade 8 vi si b le l ig ht Light is composed of different colors. The arrangement of colors of light shows the hierarchy of the colors’ corresponding energy.

5. In Grade 10 Applications of the different EM waves Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html

6. TRUE 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-assessment

7. The 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 Competencies

8. How it came about… [Contribution of different scientist] Now you go! Now you won’t! [Materials that allow/block EM waves] Sound check… [ Producing and detecting radio waves] Then there was sound… [Parts of a radio transmitter and receiver] It’s getting hotter [About infrared radiation] Screen the UV out [About UV radiation] Activities in Module 2

9. Hey Hans, the opposite could be true! A changing magnetic field produces an electric field. Hans Christian Oersted 1777-1851 James Clerk Maxwell 1831-1879 OMG! The compass needle move near the current-carrying wire. This shows electric current creates magnetic field. Activity 1: How it came about… http://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 Hertz 1857-1894 http://en.wikipedia.org/wiki/Heinrich_Hertz http://simple.wikipedia.org/wiki/Michael_Faraday Michael Faraday 1791-1867 http://soulconnection.net/glossary_in_depth/maxwell.html You got it right Maxwell. I proved the existence of EM waves! Image credit:

10. Electromagnetic waves A 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/

11. Electromagnetic 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.htm

12. 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.htm

13. 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.html The modern understanding of light and color begins with Isaac Newton.

14. Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html Image credit: http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/discovery.html Frederick 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]

15. Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html Johann Wilhelm Ritter (1776 - 1810) Image credit: http://coolcosmos.ipac.caltech.edu/cosmic_classroom/classroom_activities/ritter_bio.html In 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]

16. Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html Heinrich Rudolf Hertz (1857 - 1894) Image credit: http://en.wikipedia.org/wiki/Heinrich_Hertz He 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]

17. Image Credit: http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html Perry Spencer (1894 - 1970) invented the microwave oven In 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

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

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

20. 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.

21. Module 2: Electromagnetic Spectrum Motivation: Call me maybe Hey I just met you And this is crazy But here's my number So call me maybe (insert number here)

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

23. Now you go! Now you won’t! Activity 2

24. Identify 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. Objectives

25. Questions to be investigated What materials allow radio waves to pass through them? What materials block radio waves?

26. Materials aluminum foil transparent plastic colored paper wax paper kitchen paper towel Latex gloves Remote- controlled car

27. Procedure 2 Wrap the antenna around the remote control. Secure it with a twist-tie wire or rubber band. 1 Test the RC car if it is working.

28. Procedure 3 Use 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

29. Procedure 4 Choose 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 don’t release it until the car reached the ‘finish line’ of the distance you set.

30. Procedure 5 Start 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. 6 Wrap the remote control one at a time with the different materials. Make sure that it is completely covered.

31. Make sure you know where the forward button is.

32. 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.

33. Procedure 7 Record in Table 1 the time it took the car to cover the distance you set with the remote control covered with different materials.

34. Material covering the remote control RC car time of travel (s) Observations No cover Colored Paper Wax Paper Kitchen paper towel Transparent Plastic Aluminum Foil Latex gloves Table 1

35. 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? 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:

36. 1. 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 foil transparent plastic colored paper wax paper kitchen paper towel Latex gloves The RC car moved. The RC car did not move.

37. 3. What kind of materials allowed EM waves to pass through? 4. What kind of materials blocked EM waves? Guide Questions: Paper (cellulose) colored paper wax paper kitchen paper towel Rubber ( elastomers ) Latex gloves Plastic (polyethylene) transparent plastic Aluminum - Metallic aluminum foil

38. 5. 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. No The signal can be weakened by the material covering the remote control. Guide Questions:

39. Discussion radiowaves transmitting antenna receiving 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. Transmitter sends a control signal to the receiver using radio waves

40. Discussion 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

41. 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). Discussion Image credit: https://sites.google.com/site/waveslightandsoundunit/03---unit-lessons/04---light-waves

42. When 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 . Discussion Attenuation 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 .

43. 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 . Discussion

44. Properties of media The 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: Materials Degree of Attenuation Examples Materials Degree of Attenuation Examples air none Open space bricks medium walls wood low Door , floor, partition plaster medium partitions plastic low partition paper high Rolls of paper glass low Untinted windows concrete high Load-bearing walls, floors Tinted glass medium Tinted windows Bullet proof glass high Bullet proof windows water medium aquarium metal Very high Metal cabinet, elevator cage Living creatures medium Crowds, animals, people, plants Source: http://en.kioskea.net/contents/832-propagation-of-radio-waves-802-11

45. 2 Types of matter (substance) that affect Radio waves Conductors Copper Aluminum Silver Gold Insulators (Dielectrics) Paper Plastic Teflon Glass Ceramic Dry wood As 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.

46. Students can take the investigation further by comparing the ability of the same materials in blocking other EM Waves . Extension Activity Ionizing radiation Non-ionizing radiation

47. Students can take the investigation further by controlling variables such as the thickness of materials. Extension Activit y

48. Characteristics Activity 2: Now you go! Now you won’t! Engaging in scientifically-oriented questions Gathering evidence 5 Essential Characteristics of Scientific Inquiry What materials allow/block radio waves? Observe the car if it moves or not Infer that if the car moves, then the radio waves emitted by the transmitter pass through the material covering it Infer that if the car did not move, then the radio waves emitted by the transmitter did not pass through the material covering it

49. Characteristics Activity Providing explanation s based on evidence and scientific knowledge Evaluating explanations Justifying and communicating explanations 5 Essential Characteristics of Scientific Inquiry If 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.

50. Thank you!