Electromagnetic Waves


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Electromagnetic Waves

  1. 1. Electromagnetic Waves Students will be able to Describe polarity Reproduce the entire spectrum Page 70
  2. 2. Where? 70
  3. 3. What is an Electromagnetic Wave Wave that transfers energy without a medium Vibration of electric and magnetic fields that move through space at the speed of light Created by moving an electric charge Called electromagnetic radiation 71
  4. 4. Speed Speed in a vacuum 300,000 kilometers per second From sun to Earth? 8 minutes Light slows down when it enters a medium 72
  5. 5. Models Wave Model Light travels in many directions at once Polarizing filters block all but light in one direction 72
  6. 6. Models Particle Model Light is a tiny particle moving through space Called photon Light bump up electrons in atoms Called photoelectric effect 73
  7. 7. Electromagnetic Spectrum All electromagnetic waves travel at same speed Vary only in wavelengths and frequencies Waves you can see are called visible light 74
  8. 8. Radio Waves Long wavelength Low frequency Purpose Broadcast Waves for TV and Radio 76
  9. 9. Microwaves Shortest radio waves Cell phones Radar (Radio Detection And Ranging) 76
  10. 10. 82
  11. 11. Infrared Rays Heat waves that you feel but can not see Heat Lamps Infrared Cameras Warmer objects give off more waves than cold Satellites Locate people 77
  12. 12. Visible Light Small part of electromagnetic spectrum Longest waves = Red Shortest waves = Violet Visible light is a mixture of all wavelengths – White When bending in a new medium red bends least The color you see is what is reflected (rest of light is absorbed) 78
  13. 13. Ultraviolet Rays Much shorter waves than visible light (more energy) Very dangerous Cause damage Cancer cells Eye damage Kill bacteria (used in hospitals/labs) Sunscreen and sunglasses used to black these rays Ozone layer blocks many of these rays 78
  14. 14. X-Rays High energy Penetrates most tissues Blocked only by very dense structures Bone / Lead Used in medicine and structural analysis to look for damage 79
  15. 15. Gamma Rays Extremely high energy Used in medicine to kill cancer cells Can not penetrate Earth atmosphere Telescopes put into space to detect Discovery of astronomical events Stars, black holes, galaxies… 80
  16. 16. Review • Polarization • Spectrum – Radio Waves – Microwaves – Infrared – Visible Light – Ultraviolet – X-Ray – Gamma
  17. 17. Quiz
  18. 18. Homework Draw and label the electromagnetic spectrum. Describe one thing of importance for each part of the spectrum.