Em Spectrum
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Em Spectrum

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Em Spectrum Em Spectrum Presentation Transcript

  • Electromagnetic Spectrum
  • What is it?
    • Name given to a bunch of types of radiation
    • described as a stream of photons, which are massless particles each traveling in a wave-like pattern and moving at the speed of light
    • Radiation – energy that spreads out as it travels
    • Hotter, more energetic objects and events create higher energy radiation
    • Different waves have different amounts of energy
    • Moves in transverse wave motion
  •                     Gamma Rays                             High frequency, Short wavelength 0.01 nm X-Rays                                                   1 nm Ultra-Violet                             100 nm Visible light                             400-700 nm Infra-Red                             0.01 mm Microwaves                             1 cm Radio waves                             Low frequency, 1 m - 1km Long wavelength
  • Radio Waves
    • Wavelength – 1mm-100s m
    • Uses – radio, TV
    • Make electron in copper wire move = electric current
    • AM radio – 187m-545m
      • 750 on AM dial is 750 kHz
    • FM radio – 2.8 – 3.4 m
      • 100 on dial is 100 mHz
    • TV – 0.4 m – 5.6 m
  • Microwaves
    • 1mm to 1 m
    • Wavelength are easily absorbed by water
    • Excited water heats up and cooks food
    • Cordless phones and cell phones use microwaves
      • 16 cm –35 cm in wavelength
  • Infrared
    • Wavelength about 1 mm
    • “Infra”red =“Below” red light
    • Wavelengths longer than red visible light
    • Given off by hot objects
      • Stars, lamps, flames
    • Used by remote controls, rescue workers, “night vision,” weather forecasters
    • Used by pit vipers to detect prey
  • Visible light
    • Wavelength 700nm – 400nm
    • Only part of EM (electromagnetic spectrum) we can detect
    • White light actually contain all colors of visible spectrum
                                                                    
  • Ultraviolet
    • Ultraviolet = “Above” violet
    • 400nm-1000nm
    • Visible to insects
    • Cause sun damage to skin
    • Uses – detect bank forgeries, kill microbes
    Normal Under UV light                                   
  • X-Ray
    • Wavelength about 1 nm
    • High energy, short wavelength
      • They can go right through you, but not bones
    • Uses – evaluating bodily injuries, airport security
    • Can cause cell damage and cancer
  • Gamma Rays
    • High frequency will go through metal
      • Need lead or thick concrete to stop them
    • Can cause cancer
    • Uses- radio-therapy to treat cancer, evaluate stability of airplane wings, “irradiate” food
  • Conclusion
    • Longer wavelength = less energy
    • More energy = greater penetrating power (more danger)
    • To see all parts of EM you need to go to space
    • Stars give off all types of EM
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