Isaac Newton 1643 - 1727. Light behaves like small particles - corpuscles Light travels in straight...
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Transcript of Isaac Newton 1643 - 1727. Light behaves like small particles - corpuscles Light travels in straight...
•Light behaves like small particles - corpuscles
•Light travels in straight lines
•Reflect off opaque surfaces
•Penetrate transparent materials
White light made of colors
Newton
Problems with Reflecting Telescopes
* Longer focal length harder to make
* Chromatic Aberration
• Light behaves like waves
– 1600s Christian Huygens • Refraction & Reflection explained by
wave theory of light• Problem – can’t see around corners
– 1827 Thomas Young and Augustin Fresnel• Measures wavelength
• Observes interference of waves
http://micro.magnet.fsu.edu/primer/java/interference/doubleslit/
• 1820 Hans Christian Ørsted – Discovers relationship between electricity &
magnetism– In 1802 Italian Gian Domenico Romagnosi had
already announced this was ignored
• 1873 James Clerk Maxwell– finds the mathematical
relationship between electric fields and magnetic fields
• 1889 Heinrich Hertz – Produces small electromagnetic waves that
have properties of light– Produces Radio Waves or “Hertzian waves”
• 1914 Gamma Rays Included – Henri Becquerel “Becquerel’s Rays”
Radioactivity– Marie & Pierre Curie discover new elements
Polonium & Radium– Paul Villard finds stronger rays emitted by
radium– 1914 Ernest Rutherford measures wavelength
Early 1900sWe know “light” is a form of electromagnetic radiation
There are many different “kinds” of light or electromagnetic radiation