The Electromagnetic Spectrum

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The Electromagnetic Spectrum

• 9th Grade

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What is the electromagnetic spectrum?

• The entire range of electromagnetic wave
  frequencies is called the electromagnetic
  spectrum.

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Radio Waves

• Are low frequency electromagnetic waves with
  wavelengths from less than a centimeter to about
  1000 meters.

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Types of radio waves

• Microwaves are radio wavelengths of about 1 to 10
  cm.
• Microwaves warm up food by making the molecules
  in the food vibrate at incredible speed. 
  Sometimes the food is vibrated so fast that the
  food molecules tear and rip.  Microwaves are
  absorbed by food, but the microwaves do not make
  the food radioactive because they turn into heat
  the minute they are absorbed by food.

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Radar

• In radar, radio waves bounce off an object to
  determine its speed and location.

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MRI

• In Magnetic Resonance Imaging (MRI), radio waves
  produce an image of the inside of the body.

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Infrared Waves

• Electromagnetic waves with a slightly higher
  frequency than radio waves
• People feel them as thermal energy or warmth

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Visible Light

• Has wavelengths between 390 and 770 billionth of
  a meter and can be seen with the eye
• ROYGBIV
• Red has the longest wavelength.

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Ultraviolet Light

• Have frequencies slightly higher than visible
  light and can damage skin
• Can kill bacteria
• Can be absorbed by some fluorescent materials and
  released as visible light.

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The Ozone Layer

• Absorbs most of the Suns harmful ultraviolet
  waves.

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X-rays and Gamma Rays

• Are ultra-high-frequency electromagnetic waves
  that can travel through matter, break molecular
  bonds, and damage cells.
• X-Rays are used to provide images of bones and to
  examine suitcases at airports without opening
  them.
• Radiation therapy is used to kill diseased cells.

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