Electromagnetic Spectrum

1
Electromagnetic Spectrum

• Visible light and color
• Energy, frequency, wavelength
• Real-world uses
• Astronomy uses
• Fictional uses

2
Electromagnetic Radiation

• Radiation when things are sent out into empty
  space
• EM radiation light
• Nuclear radiation result of nuclear reactions,
  includes
• Alpha particles (Helium nucleii)
• Beta particles (positrons anti-matter
  electrons)
• Gamma particles (gamma EM radiation)

3
Summary

• Seven main types of light
• Each has uses on Earth
• Each helps us understand part of astronomical
  objects
• Need all types of light to paint the full picture

4
http//www.lcse.umn.edu/specs/labs/images/spectrum
.gif
5
What is Light?

• Electric and magnetic fields waving
• Packets of energy called photons

6
Frequency

• f, ? (Greek letter nu)
• Measured in units of Hertz (Hz)
• How many times it waves per second.
• Related to how much energy that type of light
  has.

7
Wavelength

• ? (Greek letter lambda)
• Measured in units of
• Nanometers (nm) or
• Angstroms (Å)
• 1 nm 10 Å
• How big the wave is, what size objects it can
  affect, and how big a telescope you need to see
  it.

8
Energy

• Ehfh?
• Measured in units of Joules (J) or electron-Volts
  (eV, keV)
• Related to how the light was created.

9
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
10
Visible light and color

• A small part of the total spectrum
• Approximately 400-700nm, 4000-7000Å, violet to
  red
• Each color the eye can see has a different
  wavelength.

11
http//solarsystem.nasa.gov/deepimpact/images/Spec
t-Prism-sm.jpg
12
http//wfc3.gsfc.nasa.gov/MARCONI/images-basic/spe
ctrum.jpg
13
Atmospheric Windows

• Different types of light can get through our
  atmosphere more easily, as a result of the
  chemical composition of our atmosphere (water)
• Visible light, Radio
• Combination of these atmospheric windows and of
  the size of eyes led most animals to evolve to
  see visible light

14
The Electromagnetic Spectrum
Wavelength
Frequency
High flying air planes or satellites
Need satellites to observe
15
False Color Images

• Pictures attempt to translate invisible light
  to what we can see.
• Representative color colors have meaning, such
  as specific non-visible colors or chemicals
• Touch the Universe by Noreen Grice

16
http//www.yorku.ca/eye/spectrum.gif
17
High EnergyHigh FrequencyShort Wavelength
18
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
19
?-ray (gamma)

• Very high energy
• Very high frequency (big numbers)
• Very short wavelengths (small numbers)
• On Earth radioactivity, some cancer treatment
• Astronomy high energy processes, hot
  environments colliding stars, around black
  holes, gas around galaxies

20
http//today.slac.stanford.edu/images/2007/swift-g
amma-ray-lg.jpg
21
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
22
X-ray

• High energy
• High frequency
• Short wavelengths
• Used to determine whether bones are broken, and
  teeth have cavities
• Astronomy similar to ?-ray, plus the Sun

23
http//www.atnf.csiro.au/people/mdahlem/img/xmmtel
.gif
24
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
25
Ultraviolet (UV)

• Slightly higher frequencies and shorter
  wavelengths than humans can see
• Some birds and insects can see in the UV
• UV light causes suntans, sunburn, cancer, can be
  used to sterilize equipment
• Astronomy Used to study the Sun and other hot
  objects

26
http//sohowww.nascom.nasa.gov/data/realtime/eit_1
95/1024/latest.html
27
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
28
Table of Uses
29
Low EnergyLow FrequencyLong Wavelength
30
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
31
Infrared

• Slightly longer wavelength and lower frequency
  than the human eye can see.
• Some animals including some snakes, some bats,
  and some insects can see IR.
• Temperatures of cool to warm objects, so IR
  goggles help firefighters, soldiers, and home
  insulation experts
• Some remote controls, Kinect
• Astronomy IR travels through dust so is good to
  look at young forming stars. (Spitzer Space
  Telescope)

32
http//upload.wikimedia.org/wikipedia/en/c/cf/Ir_g
irl.png
33
http//www.spitzer.caltech.edu/
34
http//gallery.spitzer.caltech.edu/Imagegallery/im
age.php?image_namessc2007-19a
35
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
36
Microwave/Sub-mm

• Low energy
• Low frequency (small numbers)
• Long wavelength (large numbers)
• Used in microwave ovens, cellphone signals
• Astronomy cooler objects such as clouds of dust,
  and the Cosmic Microwave Background (light from
  the Big Bang)

37
http//apod.nasa.gov/apod/image/0302/sky_wmap_big.
jpg
38
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
39
Radio

• Very low energy
• Very low frequency
• Very long wavelengths
• Radio transmissions for car stereos, TV,
  walky-talkies, GPS, communicate with satellites,
  weather radar, radar guns
• Astronomy cool objects such as gas clouds,
  entire galaxies, SETI (potential alien
  communications)

40
http//cache.eb.com/eb/image?id96170rendTypeId4
41
Nancay Radio Telescope
42
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
43
Each part of the wavelength tells us part of the
story.Must put together all wavelengths to get
the full story.
44
http//www.astro.utu.fi/cflynn/astroII/crab.gif
45
http//www.thunderbolts.info/tpod/2006/image06/060
123nebula.jpg
46
Multiwavelength Sun

• http//sohowww.nascom.nasa.gov/data/realtime/realt
  ime-update.html
• Putting these together helps us understand the
  layers of our dynamic Sun.

47
http//upload.wikimedia.org/wikipedia/commons/9/99
/EM_Spectrum3-new.jpg
48
Fill out this chart
Name General uses Astro uses Fictional uses
Radio
Microwave
Infrared
Visible
Ultraviolet
X-ray
Gamma-ray
49
Summary

• Seven main types of light
• Each has uses on Earth
• Each helps us understand part of astronomical
  objects
• Need all types of light to paint the full picture