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LASERS

LASERS. Does anyone have lasers at home they can share with me for a few days? We can use them for doing a lab on wave behaviors next week. Waves. How energy travels from one place to another (you need energy to start it, and it doesn’t stop until all the energy is transferred).

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LASERS

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  1. LASERS Does anyone have lasers at home they can share with me for a few days? We can use them for doing a lab on wave behaviors next week

  2. Waves • How energy travels from one place to another • (you need energy to start it, and it doesn’t stop until all the energy is transferred)

  3. What is a Wave? • A disturbance that carries energy through matter or space

  4. Mechanical Waves • Mechanical Waves- must have matter to move through called a MEDIUM • Sound waves • Earthquake waves • What is a medium (any kind of matter disturbed by the energy of a wave)

  5. What is a Wave? • What is the medium for waves at the beach?

  6. What is a Wave? • What is the medium for waves coming out of your television?

  7. What is a Wave? • What is the medium for waves in a football stadium?

  8. What is a Wave? • What is the medium for waves that cause an earthquake?

  9. Two Basic Types of Mechanical Waves Transverse and Longitudinal • 1. Transverse Waves • The disturbance runs perpendicular to the wave’s direction • Looks more like a wave at the beach

  10. Transverse Waves • Move in an up and down motion perpendicular to the direction of the wave

  11. Crest/Peak Trough Transverse Wave Anatomy Wavelength λ Amplitude Resting Point

  12. Parts of a Transverse Wave • Crest: highest point of the wave • Trough: lowest point of the wave

  13. Parts of a Transverse Wave cont’d Wavelength: () Distance between a point on one wave to the identical point on the next wave (One whole Wave) Amplitude: (a) Distance from the crest or trough of a wave to the resting point

  14. 2nd Type of Mechanical Wave • Longitudinal Waves a.k.a. Compressional Waves • Sound Waves • Some Earthquake Waves

  15. Longitudinal Wave • Matter vibrates in the direction of the wave • Energy moves parallel to the matter • Examples: Sound waves, springs, coils

  16. How does a Longitudinal wave work? • Compressions expand to an area that is less dense • Rarefaction: The less dense area in a compressional wave

  17. How Does a Longitudinal Wave Work? (Cont’d) • Wavelength (): One compression and one rarefraction

  18. When Waves Hit Things Reflection: The wave bounces off the new medium and can change direction

  19. Refraction Refraction: The wave enters a new medium and changes speed This is responsible for “weirdness” when you look at things through water – magnification, warping, etc…

  20. Diffraction Diffraction: The wave bends around corners or edges of a barrier

  21. Frequency of a wave Frequency:the number of waves that pass a point in a given amount of time. Measured in Hertz (Hz)

  22. Speed of Waves Wave speed is equal to the frequency of the wave times the wavelength. Vw = fλ (units: meters/second, or equivalent) Look at that formula – if Vw stays the same. What can you say about f and λ?

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