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WAVES: LIGHT moving

WAVES: LIGHT moving. Waves carry energy from one place to another. The NATURE of WAVES. Waves – A wave is a disturbance that transfers energy. A medium – A substance which transmits a wave. Speed of waves – depends on the properties of the medium. This drawing shows.

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WAVES: LIGHT moving

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  1. WAVES: LIGHT moving Waves carry energy from one place to another

  2. The NATURE of WAVES • Waves – A wave is a disturbance that transfers energy. • A medium – A substance which transmits a wave. • Speed of waves – depends on the properties of the medium.

  3. This drawing shows • 1. reflected energy • 2. transmitted energy • 3. emitted energy • 4. absorbed energy

  4. This drawing shows • 1. reflected energy • 2. transmitted energy • 3. emitted energy • 4. absorbed energy

  5. This drawing shows • 1. reflected energy • 2. transmitted energy • 3. emitted energy • 4. absorbed energy

  6. This drawing shows • 1. reflected energy • 2. transmitted energy • 3. emitted energy • 4. absorbed energy

  7. Light & the Electromagnetic Spectrum

  8. LIGHT: What Is It? • Light Energy • Atoms • As atoms absorb energy, electrons jump out to a higher energy level. • Electrons release light when falling down to the lower energy level. • Photons - bundles/packets of energy released when the electrons fall. • Light: a stream of Photons

  9. Electromagnetic Waves • Speed in Vacuum • 300,000 km/sec • 186,000 mi/sec • Speed in Other Materials • Light is slower in Air, Water, Glass

  10. Transverse Waves • Energy is perpendicular to direction of motion • Moving photon creates electric & magnetic field • Light has BOTH Electric & Magnetic fields at right angles!

  11. Electromagnetic Spectrum

  12. Electromagnetic Spectrum Radio Waves • Longest wavelength & lowest frequency. • Size of a football field + • Radio & T.V. broadcasting.

  13. Electromagnetic Spectrum • Microwaves • About the size of a baseball • Used in radar, cooking, pagers, cells

  14. Electromagnetic Spectrum Infrared Rays • Light rays with longer wavelength than red light. • Longer IR is heat • Cooking, Medicine, T.V. remote controls

  15. Which is the same thing as heat? • 1. Visible light 2. Infrared light 3. Radio waves 4. Ultraviolet radiation

  16. This drawing shows • 1. convection • 2. transmitted energy • 3. conduction • 4. absorbed energy

  17. This drawing shows • 1. convection • 2. transmitted energy • 3. conduction • 4. absorbed energy

  18. LandSat satellite

  19. Electromagnetic Spectrum • Visible Spectrum – Light we can see • Roy G. Biv – Acronym for Red, Orange, Yellow, Green, Blue, Indigo, & Violet. • Largest to Smallest Wavelength.

  20. Electromagnetic Spectrum Ultraviolet rays. • EM waves slightly shorter than visible light • Used in food processing & hospitals to kill germs’ cells • Helps your body use vitamin D.

  21. Electromagnetic Spectrum • X-Rays • are shorter than UV rays. • Medicine – Bones absorb x-rays; soft tissue does not. • Lead absorbs X-rays.

  22. Electromagnetic Spectrum • Gamma rays • Shortest wavelength EM waves. • They come from outer space. • Uses: cancer treatment.

  23. The Atmosphere absorbs wavelengths

  24. LIGHT: Particles or Waves? • Wave Model of Light • Explains most properties of light • Particle Theory of Light • Photoelectric Effect – Photons of light produce free electrons

  25. LIGHT: Refraction of Light • Refraction – Bending of light due to a change in speed. • Index of Refraction – Amount by which a material refracts light. • Prism – Glass that bends light. Different frequencies are bent different amounts & light is broken out into different colors.

  26. Refraction

  27. LIGHT & Reflection • Reflection – Bouncing back of light waves • Regular reflection – mirrors smooth surfaces scatter light very little. Images are clear & exact. • Diffuse reflection – reflected light is scattered due to an irregular surface.

  28. Color of Light • Color of Objects • White light is the presence of ALL the colors of the visible spectrum. • Black objects absorb ALL the colors and no light is reflected back.

  29. How You See • Retina – • Lens refracts light to converge on the retina. Nerves transmit the image • Rods – • Nerve cells in the retina. Very sensitive to light & dark • Cones – • Nerve cells help to see light/color

  30. How You See • Near Sighted – Eyeball is too long and image focuses in front of the retina • Far Sighted – Eyeball is too short so image is focused behind the retina. © 2000 Microsoft Clip Gallery © 2000 Microsoft Clip Gallery

  31. LIGHT & USES: LASERS • LASERS • Acronym: Light Amplification by Stimulated Emission of Radiation • Coherent Light – Waves are in phase so it is VERY powerful & VERY intense.

  32. Summary • Waves carry energy from one place to another • The Electromagnetic Spectrum is an arrangement of 7 kinds of radiation, based on their wavelength • Each kind of radiation has different wavelengths • Each color of light has different wavelengths

  33. Summary • Radio waves, microwaves, infrared rays, light, ultraviolet light, x-rays and gamma rays are different wavelength bands in the spectrum of electromagnetic waves • The speed of EM radiation in vacuum is approximately 186,000 miles/sec

  34. The End… © 2000 Microsoft Clip Gallery

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