# Electromagnetic Spectrum - PowerPoint PPT Presentation

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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
• 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.
• Microwaves-highest frequency rw. Food
• Most common use is cell phones.

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.