Electromagnetic Spectrum

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Electromagnetic Spectrum
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• Energy from the Sun travels as electromagnetic
  waves or EM waves.
• They are waves that transfers energy though a
  field.
• Do not require matter to transfer its
  energyoccurs in a vacuum.
• Ocean waves need water
• Sound waves need air.

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Parts of a Wave

• Crest- High point of wave.
• Trough- Low point of wave.
• Described by their physical wave features
• Amplitude- Height of wave from center line to
  crest or trough.
• Wavelength- Distance b/w 2 crests or troughs.
• Frequency- of waves passing a point each
  second.

Electromagnetic Waves
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Diagram of a Wave
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Arrangement

• Arranged according to their increasing frequency
  and decreasing wavelength.
• All electromagnetic waves travel at the same
  speed.
• Amt of energy carried by an electromagnetic wave
  increases with frequency.

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Electromagnetic Spectrum
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• Each wavelength of EM energy interacts with
  objects on Earth in a different way.
• Some are reflected and some are absorbed.
• Color results from a combination of both
  interactions.
• When light strikes a leaf, leaf absorbs red light
  and but reflects green light.
• Reflected green light enters your eyeso you see
  a green leaf.

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• Each type of matter has its own signature, called
  a reflectance curve, that shows how it reflects
  and absorbs energy.
• A reflectance curve is a graph that shows how a
  type of matter reflects visible, infrared and
  other wavelengths of light.
• Upward curve on graph indicates more of the
  wavelength is reflected.
• Downward curve on graph shows more of the
  wavelength is absorbed.

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Radio Waves

• Lowest frequencies and longest wavelengths.
• TV broadcast- Sound portion carried by AM waves
  (amplitude modulation) while picture portion
  carried as FM waves (frequency modulation).
• MRI- magnetic resonance imaging. Does not harm
  cells.
• Radio telescopes
• Microwaves-highest frequency rw. Food
• Most common use is cell phones.
• Radar

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Infrared Rays

• Cannot be seen
• Can be felt as heat- light bulbs, stove, sun.
• Warmer object more infrared rays
• Cool object absorb energy from infrared waves
  and become hotter.
• Infrared lamps keep food hot, relieve sore
  muscles, and dry paint and hair.
• Infrared camaras
• Thermograms
• Study pieces of art

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Visible Spectrum

• The only electromagnetic waves you can see.
• ROY G BIV red, orange, yellow, green, blue,
  indigo and violet.
• Half of energy given off by sun is visible light.
• Essential for photosynthesis.

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Ultraviolet Rays

• Electromagnetic waves with frequencies just
  higher than visible light.
• Energy of UV rays can kill cells.
• Used to kill germs in hospitals
• Preserve food in processing plants.
• Can be seen by many insects.
• UV rays cause your skin cells to produce Vitamin
  D
• Tanning is bodys way of protecting itself from
  UV rays. Can cause damage to skin, eyes and
  immune system

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X-Rays

• Energy of X-rays allows it to pass through
  materials.
• Used to take pictures of bone because bone
  absorbs X-rays.
• Exposure of X-rays over a long period of time can
  cause defects in cells.
• Been detected deep in space-believed to be in
  exploding stars.

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Gamma Rays

• Highest frequencies and shortest wavelengths.
• Have highest energy in spectrum.
• Radioactive materials and nuclear reactions emit
  gamma rays.
• Can penetrate 3-m of concrete.
• Gamma camara-patient is injected with a fluid
  that emits gamma rays. Move the camara over the
  body to form an image.