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Electromagnetic waves
Electromagnetic waves
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  1. 1. Applications of Electromagnetic Spectrum
  2. 2. Objectives: a. Cite examples of practical applications of the different regions of EM waves, such as the use of radio waves in telecommunications. (S10-FE-Iic-d-48) b. Discuss the practical uses of EM waves c. Describe how EM waves can be used in daily activities.
  3. 3. Electromagnetic Waves • Transverse waves without a medium! • (They can travel through empty space)
  4. 4. • They travel as vibrations in electrical and magnetic fields. – Have some magnetic and some electrical properties to them.
  5. 5. When an electric field changes, so does the magnetic field. The changing magnetic field causes the electric field to change. When one field vibrates—so does the other. RESULT-An electromagnetic wave.
  6. 6. Electromagnetic waves travel VERY FAST – around 300,000 kilometres per second (the speed of light). At this speed they can go around the world 8 times in one second.
  7. 7. Electromagnetic Spectrum—name for the range of electromagnetic waves when placed in order of increasing frequency
  8. 8. RADIO WAVES Have the longest wavelengths and lowest frequencies of all the electromagneti c waves.
  9. 9. Global Positioning Systems (GPS) measure the time it takes a radio wave to travel from several satellites to the receiver, determining the distance to each satellite.
  10. 10. A radio picks up radio waves through an antenna and converts it to sound waves. – Each radio station in an area broadcasts at a different frequency. • # on radio dial tells frequency.
  11. 11. • Audio – frequency (AF) signals – patterns of electric current variations. • Radio – frequency (RF) – high frequency radio waves. • Frequency Modulation – frequency of a wave that changes to match that of a signal.
  12. 12. MRI (MAGNETIC RESONACE IMAGING) Uses Short radio waves with a magnet to create an image.
  13. 13. MICROWAVES Have the shortest wavelengths and the highest frequency of the radio waves.
  14. 14. Used in microwave ovens. • Waves transfer energy to the water in the food causing them to vibrate which in turn transfers energy in the form of heat to the food. APPLICATIONS OF MICROWAVE
  15. 15. RADAR (Radio Detection and Ranging) • A radar system is consisting of an antenna, transmitter and a receiver. • Electromagnetic sensor used for detecting, locating, tracking, and recognizing objects of various kinds at considerable distances.
  16. 16. Terrestrial Communications • Satellite television and cellphone communication.
  17. 17. INFRARED RAYS Infrared Lies beyond the end of the visible light it is emitted by all objects.
  18. 18. Thermogram—a picture that shows regions of different temperatures in the body. Temperatures are calculated by the amount of infrared radiation given off. Therefore people give off infrared rays. Heat lamps give off infrared waves.
  19. 19. Blue and green indicate regions of cooler temperature. Red and yellow indicate warmer temperature
  20. 20. Applications of Infrared 1. Infrared Photographs – provides useful details of the vegetation of the Earth’s surface.
  21. 21. Applications of Infrared 2. Infrared Scanners – show the temperature variation of the body.
  22. 22. Applications of Infrared 3. Infrared Remote Controls
  23. 23. Applications of Infrared 4. Night vision goggles
  24. 24. Applications of Infrared 5. Autofocus cameras
  25. 25. VISIBLE LIGHT Shorter wavelength and higher frequency than infrared rays. Electromagnetic waves we can see. Longest wavelength= red light Shortest wavelength= violet (purple) light
  26. 26. When light enters a new medium it bends (refracts). Each wavelength bends a different amount allowing white light to separate into it’s various colors ROYGBIV.
  27. 27. ULTRAVIOLET RAYS Shorter wavelength and higher frequency than visible light Carry more energy than visible light
  28. 28. Some Uses of UV Radiation • Sun is the main source of ultraviolet radiation but there are also artificial sources of UV light. 1. UV lamps are used by banks to check the signature on a passbook.
  29. 29. Some Uses of UV Radiation 2. UV radiation is also used in sterilizing water from drinking fountains.
  30. 30. Some Uses of UV Radiation 3. UV radiation in sunlight produces Vitamin D in the skin and gives us tanning effect.
  31. 31. Causes your skin to produce vitamin D (good for teeth and bones)
  32. 32. Too much can cause skin cancer. Suntan or sunscreen lotions serve as filters to protect the body from UV radiation.
  33. 33. Used to kill bacteria. (Sterilization of equipment)
  34. 34. X- RAYS Shorter wavelength and higher frequency than UV- rays Carry a great amount of energy Can penetrate most matter.
  35. 35. X-rays are produced using X-ray tube. They are emitted when fast moving electrons hit a metal target. Wilhelm Conrad Roentgen discovered X-rays
  36. 36. X – RAY MACHINE
  37. 37. X – RAY MACHINE
  38. 38. Bones and teeth absorb x-rays. (The light part of an x-ray image indicates a place where the x-ray was absorbed) Long Wavelength X-rays
  39. 39. Too much exposure can cause cancer (lead vest at dentist protects organs from unnecessary exposure)
  40. 40. Short Wavelength X-rays Used by engineers to check for tiny cracks in structures. – The rays pass through the cracks and the cracks appear dark on film.
  41. 41. GAMMA RAYS Shorter wavelength and higher frequency than X- rays Carry the greatest amount of energy and penetrate the most.
  42. 42. Used to treat cancer cells in the process called radiotherapy. Can be very harmful if not used correctly.
  43. 43. The Incredible Hulk was the victim of gamma radiation.
  44. 44. Exploding nuclear weapons emit gamma rays.
  45. 45. Brief SUMMARY A. All electromagnetic waves travel at the same speed. (300,000,000 meters/second) in a vacuum. B. They all have different wavelengths and different frequencies. – Long wavelength-lowest frequency – Short wavelength highest frequency – The higher the frequency the higher the energy.

Notas del editor

  • Af –audio frequency rf – radio frequency
  • Can penetrate the flesh but not the bones.
  • Can penetrate to metal