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Electromagnetic Radiation

Electromagnetic Radiation. Electromagnetic Waves. Changing electric and magnetic fields can transmit energy across empty space Energy produced is electromagnetic radiation. Speed, Wavelength, and Frequency of EM Radiation. c (speed of light) = 3.00 x 10 8 m/s c = λ f

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Electromagnetic Radiation

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  1. Electromagnetic Radiation

  2. Electromagnetic Waves • Changing electric and magnetic fields can transmit energy across empty space • Energy produced is electromagnetic radiation

  3. Speed, Wavelength, and Frequency of EM Radiation • c (speed of light) = 3.00 x 108 m/s • c = λf • as wavelength increases, frequency decreases and vice versa

  4. The Electromagnetic Spectrum • Range of wavelengths • Logarithmic scale because it spans such a large range of values

  5. Radio Waves • Radio, television, cell phones • Transducers—convert sound into electrical signals • FM—frequency modulated (shorter) • AM—amplitude modulated

  6. Microwaves • Telecommunication—satellites • Microwave oven

  7. Infrared Radiation • Thermal radiation • Electric heater • Infrared thermometer • Remote control

  8. Visible Light • Eyes detect these waves • ROYGBIV • White light—mixture of all of the colors of the visible spectrum • See color when that wavelength is reflected

  9. Ultraviolet Radiation • Sunlight • Ozone molecules absorb most • Water purifiers • Sterilizing instruments

  10. X Rays • High energy • Medicine • Airport security

  11. Gamma Rays • Produced by nuclear reactions and by radioactive nuclei • Medical uses

  12. The Photoelectric Effect • Photons—bundles of energy • Planck’s constant • Energy of a photon is proportional to the frequency of the electromagnetic radiation. Planck’s constant is that proportionality. • h = 6.626176 x 10-34 J•s • Ephoton = h•c/λ

  13. The Photoelectric Effect • Work function • The energy required to “break” an electron out of a metallic surface—Φ • Hf = Φ + KEe • Photon energy (speed of light/wavelength) = work function + kinetic energy

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