JAMIE VAIL jbvail@netscape.net


|   structure of matter   |    fundemental forces   |    elementary particles   |    composite particles   |    atomic nuclei   |    atoms and ions   |    molecules   |    structure of the universe   |    solar neighborhood   |    galaxy   |    local group   |    local supercluster   |    electromagnetic radiation   |    wave model   |    photon model   |    spectrum   |    electromagnetic spectrum   |    wavelength & frequency   |

Structure of Matter

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Fundamental Forces

Force Type Distance Scale
Gravitational Attractive Planetary to cosmic
Electromagnetic Attractive, repulsive Atomic to human +
Strong Attractive Nuclear
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Small Structure of the Universe

1. Elementary Particles

Mass Electric
Electron ~1/2,000 -1
"Up" Quark ~1/3 ? +2/3
"Down" Quark ~1/3 ? -1/3
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2. Composite Particles
(from quarks)

Mass Electric
Proton 1 +1
Neutron 1 0

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3. Atomic Nuclei
(from protons & neutrons)

1 +1
4 +2

12 +6
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4. Atoms and Ions
(from atomic nuclei & electrons)

Mass Electric Charge
1 0
4 0
4 +1
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5. Molecules (rare in the universe)
(from atoms)

Mass Electric
32 0
18 0
46 0
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6. Large Scale Structure of the Universe

The Solar System

* Sun
* 9 Major Planets
* Satellites, Asteroids, Comets, etc.
The Sun -
A star... a glowing globe of gas
Planets -
Much smaller, solid and liquid composition
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The Solar Neighborhood

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A Scale Model

*Assume the Sun is the size of a ping-pong ball
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The Galaxy

A huge rotating system of billions of stars, including the Sun
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A Scale Model

*Assume Pluto's orbit to be the size of a ping-pong ball
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The Local Group

A group of about 25 galaxies including our own galaxy

The Local Supercluster

A group of about 10 galaxy clusters, including the Local Group
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Wavelengths of Electromagnetic Radiation

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Two Models of Light

1. Wave Model

Light is a wave of electromagnetic force


Symbol Definition
Wavelength - Distance between wave crests
f Frequency - Number of wave crests passing a fixed
point per second
c Wave Speed - Speed of a wave crest through space


The Relationship Between wavelength, frequency, and wave speed
Note that the wave speed is fixed at 3 X 108m per second

Shorter wavelengths mean Higher frequencies
Longer wavelengths mean Lower frequencies
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2. Photon Model
Light is a stream of energy "particles" called "photons"

EM radiation travels in discrete packets or (mass-less) "particles" of energy called photons
The energy of a photon, E, is ...
E = hf
where h=Planck's constant (a fixed number)
and, f=frequency
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Spectrum (plural - spectra)

A display of the wavelengths, frequencies, or photon energies received from a source of electromagnetic radiation
Spectra may exist in several forms:
*Photographic, and
*Graphical (example below)
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The Electromagnetic Spectrum

Band Wavelength Energy Per Photon
Radio 108 to 10-1 cm 1.24 X 10-12 to
1.24 X 10-3 eV
Infrared 10-1 to 8 X 10-5 cm 1.24 X 10-3 to
1.24 eV
Visible Light 8 X 10-5 to 4 X 10-5 cm 1.55 to 3.10 eV
Ultraviolet 4 X 10-5 to 10-6 cm 3.10 to 124 eV
X-Ray 10-6 to 3 X 10-10 cm 124 to 5 X 105 eV
Gamma-ray 10-10 to 10-13 cm 1.24 X 106 to
1.24 X 109 eV

Note: The divisions between the various bands of the spectrum are somewhat arbitrary and different limits are frequently used by different researchers and in different books.

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Wavelength & Frequency Across the Different Bands

All travel at the speed of light.

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