The Electromagnetic Spectrum

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The Electromagnetic Spectrum
                                                
                                                  
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Electromagnetic Waves

• Waves that are able to travel without a medium
• They consist of changing electric and magnetic
  fields in space
• Often called electromagnetic radiation
• And also called light in general
• All of these waves travel at 300,000,000 m/s or
  the speed of light (that is 669,000,000 mi/hr)
• Stars emit all of the various EM spectrum waves

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The spectrum is divided into

• Radio Waves
• Microwaves
• Infrared Waves (Rays) not in-Fred
• Visible Light
• Ultraviolet Waves (Rays) No N in this word!
• X-Rays
• Gamma Rays

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Frequency and Wavelength

• The electromagnetic spectrum is divided according
  to the frequency and wavelength of the waves
• Remember
• v f x ? so
• If the velocity is the same for all of the parts,
  then as the frequency increases, the wavelength
  gets shorter

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Radio Waves

• Lowest Freq., longest wavelength, lowest energy
  of the EM Spect.
• ? 1cm to 100s of meters
• Mainly used for communication AM, FM signals for
  radio, TV

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Radio Waves

• You CANNOT hear radio waves. They are flowing
  through the room right now.
• AM and FM are used for different radio bands.
• AM is used to send analog signals to TV, FM sends
  analog signals to TV by antenna
• AM amplitude modulated,
• FM frequency modulated
• AMkilohertz, FMmegahertz

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Radio Waves

• VHF Very High FrequencyFM radio broadcasts
• UHF Ultra High FrequencyFM TV broadcasts
• AM has been used to carry the picture signal from
  the TV broadcaster, FM the sound

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Microwaves

• Also known as high frequency radio waves
• Freq is higher than radio, energy is higher,
  wavelength shorter
• Used for communication and cooking food

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Microwaves

• Cooks or heats food by emitting a wave that
  matches the vibrations of H2O molecules. The
  constructive interference or resonance creates
  greater vibrations and the energy is transferred
  as heat.

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Infrared Waves (Rays)

• Includes Thermal Radiation
• Humans can sense this with temperature sensors in
  the skin
• Thermography is a special type of photography
  that takes pictures of temperature differences.
  Used for finding tumors, finding thermal energy
  leaks in homes, locating criminals, seeing in
  the dark
• Humans also emit this energy

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Infrared Waves (Rays)

• These have a higher frequency than microwaves,
  higher energy than microwaves, and a shorter
  wavelengthyou should see the trend by now.
• They are called Infra (lower) red because they
  are found below the wavelengths of red visible
  light
• Pit Vipers use this sense to locate prey, they
  are sensitive within 0.5 degrees of temp
  difference
• Mosquitos also use this to locate prey.ouch!

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Visible Light

• Freq. Still increasing, Amp. Still increasing, ?
  getting smaller and smaller
• This is the only part of the spectrum that we can
  SEE
• White light is divided into the various
  elementary colors by ?

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Visible Light

• The elementary colors in order of decreasing ?
  and increasing freq.
• Red
• Orange
• Yellow
• Green
• Blue
• Indigo Some do not recognize this one
• Violet

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Visible Light

• The moon is an illuminous body in that it reflect
  light, it is illuminated by a luminous body
• The sun and all stars are luminous bodies because
  they emit visible light

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Visible Light

• Night vision goggles still use visible light but
  they have an extremely strong ability to gather
  light or has a high resolution

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Ultraviolet Light (UV)

• There is no N in this word!
• Freq. Is still getting higher, amplitude higher,
  wavelength shorter
• Humans do not have the ability to see this type
  of radiation Hawks, bees, and other animals CAN
  see UV

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Ultraviolet Radiation (UV)

• It is called ultra (higher) violet because it is
  located at a slightly higher freq. And slightly
  shorter ? than Violet light
• It is emitted by the sun, it causes paint and
  plastics to break down
• It kills skin cells and is used in hospitals and
  nail salons to sterilize equipment, it also
  causes cataracts and vision damage

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X-Rays

• Freq continues to increase, ? is getting VERY
  small, and energy is getting higher
• Used to see inside of living things without
  cutting them open.
• X-ray film is exposed when X-rays hit it.

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X-Rays

• The denser atoms absorb the x-rays while the less
  dense allow the x-rays to pass through and expose
  the film.
• This is why bones and teeth and metal show up on
  X-ray films. They are made of denser atoms.
  While the soft tissues are mainly C, H, O, N
• X-rays can cause DNA shifts in sex cells and can
  lead to birth defects. Normally we do not take
  X-rays of babies or of the reproductive cell
  areas of humans within their reproductive years.

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Gamma Rays

• These have the highest frequency, shortest
  wavelength and highest energy
• They can go right through the human body and
  require several feet of metal or concrete to stop
• Emitted by radioactive decay

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Gamma Rays

• Can cause the DNA to rearrange
• These mutations can be good or bad but are often
  bad
• Used in medicine to fight cancer or to kill the
  fast multiplying cancer cells
• Also used to sterilize insects for biological
  control
• Can be used to kill bacteria, usually UV is used
  due to the lower risk

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The Electromagnetic Spectrum

• Parts Radio waves, Microwaves, Infrared waves,
  Visible light, Ultraviolet, X-rays, Gamma rays
• Humans can sense Infrared as heat, and Visible
  light with our eyes