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Light

Light. Electromagnetic Radiation EM Radiation EM Spectrum Types of EM Radiation. A. EM Radiation. Electromagnetic Radiation transverse waves produced by the motion of electrically charged particles does not require a medium speed in a vacuum = 300,000 km/s

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Light

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  1. Light • Electromagnetic Radiation • EM Radiation • EM Spectrum • Types of EM Radiation

  2. A. EM Radiation • Electromagnetic Radiation • transverse waves produced by the motion of electrically charged particles • does not require a medium • speed in a vacuum = 300,000 km/s • electric and magnetic components are perpendicular E=mc2

  3. A. EM Radiation • Photons • tiny, particle-like bundles of radiation • absorbed and released by electrons • energy increases with wave frequency

  4. B. EM Spectrum long  low f low energy short  high f high energy

  5. C. Types of EM Radiation • Radiowaves • lowest energy EM radiation

  6. C. Types of EM Radiation • Radiowaves • FM - frequency modulation • AM - amplitude modulation • Microwaves • penetrate food and vibrate water & fat molecules to produce thermal energy

  7. C. Types of EM Radiation • Infrared Radiation(IR) • slightly lower energy than visible light • can raise the thermal energy of objects • thermogram - image made by detecting IR radiation

  8. R O Y G. B I V red orange yellow green blue indigo violet C. Types of EM Radiation • Visible Light • small part of the spectrum we can see • ROY G. BIV - colors in order of increasing energy

  9. C. Types of EM Radiation • Ultraviolet Radiation (UV) • slightly higher energy than visible light • Types: • UVA - tanning, wrinkles • UVB - sunburn, cancer • UVC - most harmful, sterilization

  10. C. Types of EM Radiation • Ultraviolet Radiation (UV) • Ozone layer depletion = UV exposure!

  11. C. Types of EM Radiation • X rays • higher energy than UV • can penetrate soft tissue, but not bones • Used to be used to size shoes before harmful affects were known.

  12. Radiation treatment using radioactive cobalt-60. C. Types of EM Radiation • Gamma rays • highest energy EM radiation • emitted by radioactive atoms • used to kill cancerous cells

  13. CHECK UNDERSTANDING • 1. A light wave is an electromagnetic wave that has both an electric and magnetic component associated with it. Electromagnetic waves are often distinguished from mechanical waves. The distinction is based on the fact that electromagnetic waves ______. • a. can travel through materials and mechanical waves cannot • b. come in a range of frequencies and mechanical waves exist with only certain frequencies • c. can travel through a region void of matter and mechanical waves cannot • d. electromagnetic waves cannot transport energy and mechanical waves can transport energy • e. electromagnetic waves have an infinite speed and mechanical waves have a finite speed

  14. Check Understanding • a. Which region of the electromagnetic spectrum has the highest frequency? • b. Which region of the electromagnetic spectrum has the longest wavelength? • c. Which region of the electromagnetic spectrum will travel with the fastest speed? GAMMA RAY RADIO WAVE All waves have the same speed which depends on the medium

  15. Check Understanding • a. Which color of the visible light spectrum has the greatest frequency? • b. Which color of the visible light spectrum has the greatest wavelength? VIOLET RED

  16. Light II. Light and Color • Light and Matter • Seeing Colors • Mixing Colors

  17. A. Light and Matter • Opaque • absorbs or reflects all light • Transparent • allows light to pass through completely • Translucent • allows some light to pass through

  18. B. Seeing Colors • White light • contains all visible colors - ROY G. BIV • In white light, an object… • reflects the color you see • absorbs all other colors ABSORBS ALL COLORS REFLECTS ALL COLORS

  19. B. Seeing Colors Video: How Cones and Rods Work • The retina contains… • Rods - dim light, black & white • Cones - color • red - absorb red & yellow • green - absorb yellow & green • blue - absorb blue & violet Stimulates red & green cones Stimulates all cones

  20. Test for red-green color blindness. B. Seeing Colors • Color Blindness • one or more sets of cones does not function properly

  21. C. Mixing Colors • Primary light colors • red, green, blue • additive colors • combine to form white light • EX: computer RGBs View Java Applet on primary light colors.

  22. C. Mixing Colors • Filter • transparent material that absorbs all light colors except the filter color View Java Applet on filters.

  23. C. Mixing Colors • Pigment • colored material that absorbs and reflects different colors • Primary pigment colors • cyan, magenta, yellow • subtractive colors • combine to form black • EX: color ink cartridges

  24. C. Mixing Colors Light Pigment When mixing pigments, the color of the mixture is the color of light that both pigments reflect.

  25. Bill Nye Explains Color

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