The%20Electro-Magnetic%20Spectrum

1
The Electro-Magnetic Spectrum
2
EM Waves

• Have properties of waves
• Crests troughs
• Reflect refract (bend)
• and particles
• Can travel through space

3
Properties of Waves

• Wavelength length of a wave from peak to peak
• Period the amount time it takes for a wave to
  pass
• Frequency number of waves/unit time
• Amplitude height or depth of a wave

4
Introduction to Waves

• PhET Lab p. 59 in lab book
• Click on Waves on a String
• Answer the questions in your lab book

5
EM Spectrum

• Spectrum means a range
• EM spectrum ranges from long wavelengths to short

• Shorter wavelength higher energy
• Highest energy waves are bad for our bodies

6
(No Transcript)
7
Visible Light
8
Visible Light

• Not all animals see the same wavelengths as
  humans
• Some see shorter wavelengths (ultraviolet)
• Hummingbirds
• Bees
• Others see longer wavelengths (infrared)
• Bats
• Snakes

9
Visible Light vs. UV

• Flower in visible light

Flower in UV light
10
Visible Light vs. Infrared
Bats in visible light

• Bats in infrared light

11
Full Visible Spectrum

• Red Orange Yellow Green Blue Violet
• (Indigo)

12
What does this have to do with Astronomy??
13
(No Transcript)
14
How do we know what a star is made of??

• By looking at its EM spectrum
• The stars fingerprint

Hydrogen
15
How light or electromagnetic radiation is used in
Astronomy

• Astronomers use a tool called a spectroscope to
  separate starlight into its colors in this way,
  they can tell what a star is made of, its
  temperature, luminosity and so on
• Astronomers can look at astronomical objects at
  different wavelengths

16
Emission Spectra
Full spectrum
Wavelengths
H
17
Models of a Hydrogen Atom

• Read p. 60 in your lab book
• Go toPhET's Model of a Hydrogen Atom
• Answer the questions on the back of p. 59