Interference and Diffraction. This Presentation is Brought to You by Interference and Diffraction. 10/28/2019 5:28 AM

Light - what is it? Particles or Waves? 200 year debate started in 1700’s. Supposedly settled in 1802. Finally resolved in early 1900’s. Before the 1700’s! 10/28/2019 5:28 AM

Jean-Baptiste Biot (1774-1862) The Particle Theorists Pierre Simon Laplace (1749-1827) Sir Isaac Newton (1642-1727) Support later provided by: Jean-Baptiste Biot (1774-1862) Sir David Brewster (1781-1868) 10/28/2019 5:28 AM

The Wave Theorists Support later provided by: Thomas Young (1773-1829) Rene DesCartes Christian Huygens Robert Hooke (1596-1650) (1629-1695) (1635-1703) Support later provided by: Thomas Young (1773-1829) Max Planck (1858-1947) 10/28/2019 5:28 AM

Speed of Light Speed in Vacuum Speed in Other Materials 300,000 km/sec 186,000 mi/sec Speed in Other Materials Slower in Air, Water, Glass 10/28/2019 5:28 AM

The Electromagnetic Spectrum A range of light waves extending in wavelength from radio waves to gamma rays. Radio Waves - communication Microwaves - used to cook Infrared - heat Visible Light - detected by your eyes Ultraviolet - causes sunburn X-rays - penetrates tissue Gamma Rays - most energetic 10/28/2019 5:28 AM

The Visible Spectrum A range of light waves extending in wavelength from about 400 to 700 nanometers.

Electromagnetic Spectrum 10/28/2019 5:28 AM

Francesco Grimaldi (1618-1663), Italian mathematician, physicist, and artist, first noticed interference fringes looking at the shadow of an opaque object. LNK2LRN 10/28/2019 5:28 AM

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How light Diffracts and Interferes with itself as it passes through 2 narrow openings. LNK2LRN 10/28/2019 5:28 AM

Thomas Young demonstrated diffraction and interference of light in 1802. Is this an example of chromatic aberration? LNK2LRN And remember, “Blue bends best!” 10/28/2019 5:28 AM

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LNK2LRN λ = x·d / L or λ = d·sinθn / n How to derive the equation for λ , the wavelength of light. x λ λ = x·d / L or λ = d·sinθn / n LNK2LRN 10/28/2019 5:28 AM

Violet 410-440 Blue 440-490 Green 490-540 Yellow 540-600 Correlation of spectrum color with wavelength (nanometers). Color Wavelength (nm) Violet 410-440 Blue 440-490 Green 490-540 Yellow 540-600 Orange 600-630 Red 630-770 10/28/2019 5:28 AM

X-ray diffraction allows us to see the molecular lattice in a crystal. LNK2LRN 10/28/2019 5:28 AM

The arrangement of atoms in a crystal. LNK2LRN 10/28/2019 5:28 AM

THE END. Next Topic: Electric Forces and Fields. 10/28/2019 5:28 AM