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Chapters 10 & 11

Chapters 10 & 11. Waves, Color & Light. Waves. What is a wave?. Vibration that occurs in a certain amount of time Simple harmonic motion – up and down or back and forth Movement of energy only, matter does not move!. Types of Waves. How are the two main types of waves different?.

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Chapters 10 & 11

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  1. Chapters 10 & 11 Waves, Color & Light

  2. Waves • What is a wave? • Vibration that occurs in a certain amount of time • Simple harmonic motion – up and down or back and forth • Movement of energy only, matter does not move!

  3. Types of Waves • How are the two main types of waves different? • Transverse • Wave motion is at right angles to the direction of the wave • Ex. EM waves • Longitudinal • Wave motion follows the direction of the wave • Ex. Sound waves

  4. Types of Waves • How are the two main types of waves similar? • All waves transfer energy regardless of their type

  5. Wave Properties • What are the main parts of a transverse wave? • Crest • Top • Peak • Trough • Lowest point • Valley • Together they make a sine wave

  6. Wave Properties • What are the parts of a longitudinal wave? • Compression – material is close together • Rarefaction – material is farther apart

  7. Wave Properties • How can we measure a wave? • Amplitude (A) • Half the distance between the crest and trough of the wave • Wave “height” • Wavelength (λ) • Horizontal distance between identical adjacent points on a wave, usually crest to crest

  8. Wave Properties

  9. Wave Properties • What is frequency? • Frequency (f) • Number of waves/cycles in a given period of time, usually one second • Unit: Hertz – Hz or 1/s

  10. Speed of Sound • Sound travels at 340 m/s • Light travels at 300000000 m/s • See the light before you hear the sound • Why do you see fireworks or lightning before you hear them?

  11. The Doppler Effect • What happens to waves that come from a moving source? • Doppler Effect • Waves in front of the source get bunched together • Shorter wavelength • Higher frequency • Waves behind the source are farther apart • Longer wavelength • Lower frequency

  12. The Doppler Effect

  13. Electromagnetic Spectrum

  14. Electromagnetic Spectrum • As wavelength increases, frequency decreases • Indirect relationship What is the relationship between wavelength and frequency?

  15. The Doppler Effect - Light • How does the Doppler Effect work with light? • Shift in color • Blue shift • Shorter wavelength • Higher frequency • Moving to • Red shift • Longer wavelength • Lower frequency • Moving away

  16. Visible Light

  17. Examples of EM Radiation • Radio • TV broadcasting • AM and FM broadcast radio • Avalanche beacons • Heart rate monitors • Cell phones What are some common examples of non-visible EM energy?

  18. Examples of EM Radiation • Microwaves • Microwave ovens • Bluetooth headsets • Wireless internet • Weather Radar • GPS What are some common examples of non-visible EM energy?

  19. Examples of EM Radiation • Infrared • Night vision goggles • Remote controls • Heat-seeking missiles • Heat lamps What are some common examples of non-visible EM energy?

  20. Examples of EM Radiation • Ultraviolet • Black lights • Sterilizing medical equipment • Water disinfection • Security images on money • Tanning beds What are some common examples of non-visible EM energy?

  21. Examples of EM Radiation • X-rays • Medical imaging • Airport security • Inspecting industrial welds What are some common examples of non-visible EM energy?

  22. Examples of EM Radiation • Gamma • Food irradiation • Cancer treatment • Soil density • Treating wood flooring What are some common examples of non-visible EM energy?

  23. Electromagnetic Spectrum Percent of each type that reaches the surface.

  24. Color • Why do objects appear to be certain colors? • Based on the frequency of light we see with our eyes • We normally only see the colors that an object is reflecting

  25. Primary Colors • What are the primary colors? • Red, green and blue • When these three colors of light are combined they created white light

  26. Secondary Colors • How are the secondary colors created? • Color addition - cyan, yellow and magenta which are created by adding two or more primary colors • Complementary colors - two colors that added together make white

  27. Color Addition and Subtraction • How is color subtraction different from addition? • With subtraction, you put a filter between your eyes and the light • A filter absorbs (subtracts) certain colors and allows others to pass through

  28. Color Subtraction

  29. Dyes and Pigments • What are inks, dyes and pigments? • Particles that absorb certain colors • Mixing pigments does not get the same result as mixing light

  30. Mixing Pigments • What colors make up a picture printed in a book? • Subtractive primaries, which are magenta, cyan and yellow • These colors absorb some light and reflects others which gives a picture its color

  31. Why is the sky blue? The sky is blue because oxygen and nitrogen particles absorb light and reemit (release) it as blue and violet. Our eyes are not sensitive enough to see violet though.

  32. Why are sunsets red? There is more atmosphere through which the sunlight travels. This allows for more scattering of the other colors and red to be transmitted.

  33. Why are clouds white? Different sized groups of water droplets scatter different wavelengths of light which makes clouds bright and white.

  34. Light and Color

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