The Electromagnetic Spectrum
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 The
electromagnetic spectrum is the complete
spectrum (or continuum) of all forms of “light”
 An
electromagnetic wave consists of electric and
magnetic fields which vibrate - thus making waves.
 Vibrations
2
 The









electromagnetic spectrum consists of:
radio waves
cell phone waves
microwaves
radar waves
infrared waves
visible light waves
ultraviolet waves
x-ray waves
gamma waves
The Electromagnetic Spectrum
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The Electromagnetic Spectrum
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 Properties
of electromagnetic waves include speed,
frequency and wavelength
 Speed
(s), frequency (f) and wavelength (l) are related
in the formula:
s
=f
x
l
light waves travel at a speed of 3 x 108 m/s in a
vacuum
 All
The Electromagnetic Spectrum
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 All
parts of the electromagnetic spectrum
travel at the same speed
 Therefore,
wavelength and frequency have an
indirect relationship.
 This
means that as one characteristic increases,
the other decreases
 In
other words, as wavelength increases,
frequency decreases
The Electromagnetic Spectrum
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 As
wavelength decreases, frequency will?
 increase
 See
the relationship
The Electromagnetic Spectrum
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 Electromagnetic wave characteristics:
• short wavelengths have a high frequency
• long wavelengths have a low frequency
 Electromagnetic waves & Energy:
• high frequency waves have high energy
• low frequency waves have low energy
The Electromagnetic Spectrum
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Fill in the table below:
wavelength
frequency
energy
long
high
The Electromagnetic Spectrum
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smaller wavelengths
increasing frequency
increasing energy
If you haven’t already, sketch this drawing into your
notes. Don’t worry so much about the actual
wavelengths, just get the general shape and where the
various forms of light (radio, infrared, x-ray, etc) exist.
The Electromagnetic Spectrum
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The Electromagnetic Spectrum
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 Low
energy waves with longest wavelengths
 Includes FM, AM, radar and TV waves
 Wavelengths of 1 m (10 -1 m) and longer
 Low frequency
 Used in many devices such as remote control items,
cell phones, wireless devices, etc.
The Electromagnetic Spectrum
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 Only
radio waves are longer
 Wavelength 1 x 10-1 m to
10 - 4 m (1 m to 0.001 m)
1x
 used
for communication,
medicine and consumer use
(microwave ovens)
The Electromagnetic Spectrum
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 Invisible
electromagnetic waves
that are detected as heat
 Can
be detected with special
devices such as night goggles
 Used
in heat lamps
 Higher
energy than microwaves but
lower than visible light
The Electromagnetic Spectrum
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 The
portion of the electromagnetic spectrum that
human eyes can detect
 ROY
G BIV (red, orange, yellow, green, blue, indigo,
violet)
 Which

color has the lowest frequency?
red has the lowest frequency – violet the highest
The Electromagnetic Spectrum
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The Electromagnetic Spectrum
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 Higher
 Can
energy than light waves
cause skin cancer and blindness in humans
 Used
in tanning beds and sterilizing equipment
The Electromagnetic Spectrum
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 High
energy waves
 Used
in medicine, industry
and astronomy
 Can
cause cancer
The Electromagnetic Spectrum
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 Highest
energy
 Blocked
from Earth’s
surface by atmosphere
The Electromagnetic Spectrum
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The Electromagnetic Spectrum
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①
What is the relationship between
frequency and wavelength?
①
What characteristic of gamma waves
gives them their high energy?
①
What does ROY G BIV mean? What
part of the electromagnetic spectrum
does it refer to?
The Electromagnetic Spectrum
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④
Which color is more energetic, red or
yellow?
⑤
Which type of wave travels faster,
gamma or radio?
⑥
Why are microwaves more dangerous
than radio waves?
The Electromagnetic Spectrum
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⑦
You have just been involved
in a traffic incident that leaves
you stranded on the side of
the road. Which part of the
electromagnetic spectrum
would be of the most use to
you and why?
The Electromagnetic Spectrum
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①
Frequency and wavelength are properties of waves and since speed is constant for
em waves, as frequency increases, wavelength decreases. In other words, they
have an indirect relationship.
①
Gamma waves get their high energy from their extremely short wavelengths (or
extremely fast frequency)
①
ROY G BIV stands for “red, orange, yellow, green, blue, indigo, and violet. They
are the colors of the visible light in order of longest wavelength to shortest
wavelength.
①
Yellow is more energetic than red because it has a shorter wavelength (or larger
frequency)
①
Gamma waves and radio waves travel at the same speed
①
Microwaves are more dangerous than radio waves because they have a higher
frequency and carry more energy.
The Electromagnetic Spectrum
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The Electromagnetic Spectrum
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