Download Unit 3 Lesson 3: Electromagnetic Spectrum

Electromagnetic
Spectrum
Unit 3 Lesson 3
     
Unit 3 Lesson 3 The Electromagnetic Spectrum
Florida Benchmark
•  SC.7.P.10.1 Illustrate that the sun’s energy
arrives as radiation with a wide range of
wavelengths, including infrared, visible, and
ultraviolet, and that white light is made up of a
spectrum of many different colors.
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Waves… a review
 Most
waves are either
longitudinal or transverse.
 Sound waves are longitudinal.
 But all electromagnetic waves
are transverse…
?
?
Unit 3 Lesson 3 The Electromagnetic Spectrum
Electromagnetic Light Show
What is the nature of light?
•  Light waves are different from other kinds of
waves.
•  When an electrically charged particle vibrates, its
fields also vibrate, producing an electromagnetic
(EM) wave.
•  Light waves are vibrating electric and magnetic
fields that transfer energy through space.
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Electromagnetic waves
  Produced
by the movement of
electrically charged particles
  Can travel in a “vacuum” (they do
NOT need a medium
  Travel at the speed of
light
  Also known as EM waves
Wave-particle Duality
  Light
can behave like a wave or like
a particle
  A “particle” of light is called a photon
Unit 3 Lesson 3 The Electromagnetic Spectrum
What is the nature of light?
•  EM waves travel as perpendicular electric and
magnetic fields.
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Unit 3 Lesson 3 The Electromagnetic Spectrum
What is the nature of light?
•  Radiation is energy that has been transmitted by
waves or particles. This transfer of energy is called
EM radiation.
•  All EM waves move at the same speed in a
vacuum: the speed of light.
•  EM waves can travel through many materials.
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Unit 3 Lesson 3 The Electromagnetic Spectrum
What determines the color of light?
•  Different wavelengths of light are perceived by our
eyes as different colors.
•  White light is what we perceive when we see all
the wavelengths of light at once, in equal
proportions.
•  Our eyes only register three colors of light: red,
green, and blue. All other colors we see are a
mixture of these three colors.
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Unit 3 Lesson 3 The Electromagnetic Spectrum
Invisible Colors
What are the parts of the EM spectrum?
•  The range of frequencies that EM waves can have
are called the electromagnetic (EM) spectrum.
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Radio waves
  Longest
wavelength EM waves
  Uses:
TV broadcasting
  AM and FM broadcast radio
  Avalanche beacons
  Heart rate monitors
  Cell phone communication
 
Microwaves
  Wavelengths
from 1 mm- 1 m
  Uses:
Microwave ovens
  Bluetooth headsets
  Broadband Wireless Internet
  Radar
  GPS
 
Infrared Radiation
  Wavelengths
in between microwaves
and visible light
  Uses:
Night vision goggles
  Remote controls
  Heat-seeking missiles
 
Visible light
  Only
type of EM wave able to be
detected by the human eye
  Violet is the highest frequency light
  Red light is the lowest frequency
light
Ultraviolet
  Shorter
light
  Uses:
wavelengths than visible
Black lights
  Sterilizing medical equipment
  Water disinfection
  Security images on money
 
Ultraviolet (cont.)
UVA
UVB and UVC
Energy Highest of UV
waves
Lower than UVA
Health
risks
 
Extremely
low risk for
DNA damage
  Can destroy
Vitamin A in
skin
 
Can cause DNA
damage, leading to
skin cancer
  Responsible for
sunburn
X-rays
  Tiny
wavelength, high
energy waves
  Uses:
Medical imaging
  Airport security
  Inspecting industrial welds
 
Gamma Rays
  Smallest
wavelengths, highest
energy EM waves
  Uses
Food irradiation
  Cancer treatment
  Treating wood flooring
 
Unit 3 Lesson 3 The Electromagnetic Spectrum
Star Light, Star Bright
How much of the sun’s energy reaches
us?
•  Most of the sun’s energy is in the narrow visible
light range, but the sun gives off some radiation in
every part of the spectrum.
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Unit 3 Lesson 3 The Electromagnetic Spectrum
How much of the sun’s energy reaches
us?
•  Not all wavelengths of light penetrate the
atmosphere equally. Radio waves penetrate the
atmosphere easily.
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Unit 3 Lesson 3 The Electromagnetic Spectrum
How much of the sun’s energy reaches
us?
•  Some EM radiation can be dangerous to humans,
so we take extra steps to protect ourselves.
•  UV light can be harmful. It can penetrate clouds.
•  In space, the dangers from EM radiation are very
high because there is no atmosphere to filter the
radiation.
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Unit 3 Lesson 3 The Electromagnetic Spectrum
Frequency Asked Questions
How much energy does EM radiation
have?
•  Different frequencies of EM waves carry different
amounts of energy.
•  High-frequency EM waves have more energy than
low-frequency EM waves.
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Unit 3 Lesson 3 The Electromagnetic Spectrum
How much energy does EM radiation
have?
•  Because low-frequency waves, such as radio
waves, carry less energy, they are safer. Walkietalkies and baby monitors use radio waves.
•  High-frequency waves, such as UV light, carry
more energy and can be harmful. UV light causes
sunburns, and X-rays require precautions.
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Unit 3 Lesson 3 The Electromagnetic Spectrum
Fire in the Sky
•  The stream of electrically charged particles from
the sun is called the solar wind.
•  When solar wind encounters Earth’s magnetic
field, the particles are accelerated.
•  When the accelerated particles collide with the
atmosphere, they give off EM radiation in the form
of light.
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Unit 3 Lesson 3 The Electromagnetic Spectrum
Fire in the Sky
•  Near the poles, the accelerated particles form an
aurora that can light up the sky.
•  The aurora at the North Pole is called the aurora
borealis. At the South Pole, it is called the aurora
australis.
•  The color of the aurora depends on the type of
atoms in the atmosphere that react with the solar
wind.
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