Isaac Newton 1643 - 1727

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Isaac Newton 1643 - 1727
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White light made of colors

• Light behaves like small particles - corpuscles
• Light travels in straight lines
• Reflect off opaque surfaces
• Penetrate transparent materials

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Newton Problems with Reflecting Telescopes
Longer focal length harder to make Chromatic
Aberration
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Newtonian Telescope
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• Light behaves like waves
• 1600s Christian Huygens
• Refraction Reflection explained by wave theory
  of light
• Problem cant see around corners

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By 1800Light has component partsLight behaves
as a particle
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Discovers Infra-red
William Herschel 1738 1822
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• 1801
• Johann Wilhelm Ritter

discovers Ultraviolet Light
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• 1827 Thomas Young and Augustin Fresnel

Measures wavelength Observes interference of
waves
http//micro.magnet.fsu.edu/primer/java/interferen
ce/doubleslit/ http//www.youtube.com/watch?vGzbK
b59my3U
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• 1820 Hans Christian Ørsted

Discovers relationship between electricity
magnetism In 1802 Italian Gian Domenico Romagnosi
had already announced this was ignored
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• 1845 Michael Faraday

Predicts Fields around objects
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Electric Fields
Magnetic Fields
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• Michael Faraday
• Light affected by a magnetic field

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• 1873 James Clerk Maxwell

finds the mathematical relationship between
electric fields and magnetic fields
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Electromagnetic Waves

1. Visible light is EM energy
2. There should be other EM frequencies

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• 1889 Heinrich Hertz

Produces small electromagnetic waves that have
properties of light Produces Radio Waves or
Hertzian waves
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• 1895 Wilhelm Roentgen

Discovers X - Rays
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• By 1900
• Light, Radio and X-rays are Electromagnetic Waves

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• 1930 Microwaves Explored
• WW II pushes research
• Commercial Research after war

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• 1914 Gamma Rays Included
• Henri Becquerel
• Marie Pierre Curie
• Paul Villard finds
• 1914 Ernest Rutherford

Becquerels Rays Radioactivity
discovers new elements Polonium Radium
stronger rays emitted by radium
measures wavelength
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• Early 1900s
• We know light is a form of electromagnetic
  radiation
• There are many different kinds of light or
  electromagnetic radiation

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Think of Light as a stream of particles Each
particle has a certain amount of energy
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• Is Light a Wave or a Particle?

Wave Particle Duality