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Electromagnetic Spectrum

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Electromagnetic Spectrum Energy from the Sun travels as electromagnetic waves or EM waves. They are waves that transfers energy though a field. – PowerPoint PPT presentation

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Title: Electromagnetic Spectrum


1
Electromagnetic Spectrum
2
  • 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.

3
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
4
Diagram of a Wave
5
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6
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.

7
Electromagnetic Spectrum
8
  • 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.

9
  • 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.

10
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11
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

12
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

13
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14
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.

15
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

16
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.

17
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18
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.
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