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Exploring Electromagnetic Waves in the Universe

Discover the fascinating world of electromagnetic waves - from the constantly changing electric and magnetic fields to the diverse spectrum of radio waves, microwaves, and gamma rays. Learn about the behavior of light, reflection, refraction, and polarization, and explore how these waves interact with matter in our environment.

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Exploring Electromagnetic Waves in the Universe

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  1. Electromagnetcetera… Chapter 18

  2. Electromagnetic Waves • Constantly changing fields: • Electric field • Magnetic field

  3. EMW’s • Produced when electric charge vibrates or accelerates ***Do NOT need a medium to travel in. *Electromagnetic Radiation – transfer of energy by EMW through matter or space

  4. Speed of EMW’s • In a vacuum… ALL EMW’s travel same speed. c = 3.00 X 108 m/s • EMW’s vary in wavelength and Hz. • S = W X F

  5. Wave or Particle? WAVE = -Thomas Young (P. 536) -Experiment showed bands of interference PARTICLE = -photoelectric effect -Einstein (photons – packets of energy)

  6. Phillip Lenard – experimented/coined term…

  7. Intensity • Light (photons) travel outward from source in ALL directions. • Intensity decreases as light travels farther…

  8. Electromagnetic Spectrum

  9. Radio Waves • Amplitude Modulation – amplitude is varied (AM stations) • Frequency Modulation – frequency varied (FM stations) (Television) **Radio waves = longest waves

  10. Microwaves • Cook food • Cell phones • Radar • Cops • Baseball

  11. Infrared Rays • Used to discover sources of heat and heat differences • Marijuana (heat lamps) • Heat source • Fast food

  12. Visible Light • Only light human eye can see.

  13. Ultraviolet Rays • Source of vitamin D • Medicine, agriculture (greenhouses) • UVA, UVB? • Wear sunscreen?

  14. X-Rays • Can penetrate matter that light can’t. • Medical, dental x-rays • Airport, courthouses, etc.

  15. Gamma Rays • Shortest wavelengths • Overexposure = death • Treat cancer - radiation

  16. Light Behavior • Transparent • Translucent • Opaque

  17. Reflection • Regular • mirror • Diffuse • rough surface

  18. Refraction Light bends or curves

  19. Polarization • Polarized light vibrates in one plane • Vertical or horizontal • Sunglasses • Car visors

  20. Scattering • Light is redirected as it passes through a medium • Why is the sky blue? • Blue light scatters the most… filling the sky… to make it appear blue… but…

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