The Electromagnetic Spectrum (PowerPoint download)

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					MAP TAP 2003-2004   The Electromagnetic Spectrum   1
                    What is it?
• The electromagnetic spectrum is the complete
  spectrum or continuum of light including radio
  waves, infrared, visible light, ultraviolet light, X-
  rays and gamma rays
• An electromagnetic wave consists of electric and
  magnetic fields which vibrates thus making
  waves.




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                        Waves
• Properties of waves include speed, frequency
  and wavelength
• Velocity (v), frequency (f) and wavelength (l) are
  related in the formula v = lf
• All light travels at a speed of 3 x 108 m/s in a
  vacuum




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        Wavelength, Frequency and
                 Energy
• Since all light travels at the same speed,
  wavelength and frequency have an indirect
  relationship.
• Light with a short wavelength
      *high frequency
      * high energy
• Light with a long wavelength
      *low frequency.
      *low energy
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                    Radio waves
•   Low energy waves with long wavelengths
•   Includes FM, AM, radar and TV waves
•   Low frequency
•   Used in many devices such as remote control
    items, cell phones, wireless devices, etc.




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                    Microwaves
• Shorter than radio, longer
  than light and infrared
• First used in radar, now
  used in communication,
  medicine and consumer
  use (microwave ovens)




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                    Infrared waves
• Invisible electromagnetic waves
  that are detected as heat
• Can be detected with special
  devices such as night goggles
• Used in heat lamps
• Higher energy than microwaves
  but lower than visible light




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                    Visible Light
• The portion of the electromagnetic spectrum
  that human eyes can detect
• ROY G BIV (red, orange, yellow, green, blue,
  indigo, violet)
• Red is the lowest frequency and violet is the
  highest frequency




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                    Ultraviolet waves
• Higher energy than light waves
• Can cause skin cancer and blindness in
  humans
• Used in tanning beds and sterilizing
  equipment




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                       X-Rays
• High energy waves
• First discovered by
  Roentgen
• Used in medicine,
  industry and astronomy
• Can cause cancer




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                    Gamma rays
• Generated by radioactive
  atoms and in nuclear
  reactions
• Highest energy
• Blocked from Earth’s surface
  by atmosphere




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                    Time to think…..
•    1. What is the relationship
     between frequency and
     wavelength?

•    2. What is meant by ‘spectrum’?

•    3. What does ROY G BIV mean?



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              Now, let’s really think
• 4. Can you actually see x-rays?
    – Support your answer.
• 5. Which color is more energetic, red
  or yellow?
• 6. Which type of wave travels faster,
  gamma or radio?
• 7. Why are microwaves more
  dangerous than radio waves?


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                    Think about it….
• You have just been involved
  in a traffic incident that
  leaves you stranded on the
  side of the road. Which part
  of the electromagnetic
  spectrum would be of the
  most use to you and why?




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posted:8/6/2011
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