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Nature of Light

Nature of Light. And God said, Let there be light: and there was light. And God saw the light, that it was good: and God divided the light from the darkness. - Genesis 1:3-4

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Nature of Light

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  1. Nature of Light • And God said, Let there be light: and there was light. And God saw the light, that it was good: and God divided the light from the darkness. - Genesis 1:3-4 • And God said, This is the token of the covenant which I make between me and you and every living creature that is with you, for perpetual generations: I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth. - Genesis 9:12-13

  2. Rainbow Bridge

  3. What is light?

  4. Early Observations • Empedocles (500 BC) • Light has motion and travels at a fixed speed • Aristotle (332 BC) • Pure light changed into colors by contamination • Egyptians (200 AD) • Light travelels from eye to illuminate object • Alhazen (965 AD) • Light comes from sun or other objects • Made curved mirrors and pinhole camera obscura

  5. Early Observations • Leonardo da Vinci • Studied the ''Artificial Rainbow'' obtained by passing pure light through a prism • Galileo (1600) • Tried to measure speed of light

  6. Early Observations • Newton • Studied chromatic aberration in lenses • Studied light passing through prisms • Selected the brightest seven: Red, Orange, Yellow, Green, Blue, Indigo, and Violet • These are arbitrary • Thought light was comprised of corpuscles • Unable to completely explain color • Nature and Nature's Law lay hid at night.God said, 'Let Newton be,' and all was light.

  7. Early Observations • Christian Huygens • Published the wave theory of light in 1690 • Could easily explain refraction • Hard to explain light travelling in a vacuum • Light carried on ''ether'' • Thomas Young (1801) • Double slit experiment • Determined wavelength of red light of 750 nm • Augustin Jean Fresnel (1816) • Created diffraction gratings

  8. Electromagnetic Radiation • Sir William Herschel (1799) • Using a prism and a thermometer discovered infrared radiation • Showed it behaves like visible light • Johann Wilhelm Ritter • Used silver chloride to detect ultraviolet light • James Clerk Maxwell (1864) • Theorized radiation beyond infrared • Produced and identified in 1887 by Heinrich Hertz

  9. Dual Nature of Light • Max Planck • Radiation has a wave form • Made of small units of energy, called a quanta • Unified earlier theories • On Monday, Wednesday, and FridayWaves boasted, ''It's my day,''On Tuesdays, Thursdays, and SaturdayParticles sang, ''Due it my way.''Sundays, though, were the very bestThe good Lord said, ''It's a day of rest.''

  10. Electromagnetic Radiation

  11. X-Rays • Wilhelm Konrad Roentgen (1895)

  12. Roentgen Rays • The Roentgen Rays, the Roentgen RaysWhat is this craze:The town's ablazeWith the new phraseOf x-rays' ways.I'm full of daze,Shock and amazeFor nowadaysI hear they'll gazeThro' cloak and gown – and even stays,Those naughty, naughty Roentgen Rays.

  13. Roentgen Rays • We do not want, like Dr. Swift,To take off our flesh and pose inOur bones, or show each little riftAnd joint fro you to poke your nose in. - London's Punch magazine, 1896

  14. Polarization

  15. Interference

  16. Diffraction

  17. Reflection

  18. Refraction

  19. Total Internal Reflection

  20. Prisms and Lenses • Early lens dicovered in ruins of Nineveh believed to be 4000 years old

  21. Concave lenses

  22. Convex lenses

  23. Speed of Light • Galileo • Used lanterns separated by increasing distances • No valuable estimate • Olaus Roemer (1675) • Used eclipses of Jupiter's satellites • Obtained a speed of 140,000 miles per second • Riduculed by the French Academy of Sciences:''It is absolutely impossible for anything, unless by the spirit of God, to attain such a a speed''

  24. Speed of Light • Jean Bernard Leon Focault (1850) • Used a rotaing mirror system • Obtained a speed of 187,000 miles/sec • Albert Abraham Michelson (1879) • Obtained a speed of 186,284 miles/sec • Current Speed is 186,284 miles/sec

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