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WAVES

WAVES. WAVES. a disturbance that transfers energy. Carries energy from one place to another Classified by what they move through Mechanical Waves the energy is transferred by vibrations of medium (medium = matter) ex/ ocean waves move through water

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WAVES

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  1. WAVES

  2. WAVES a disturbance that transfers energy • Carries energy from one place to another • Classified by what they move through • Mechanical Wavesthe energy is transferred by vibrations of medium (medium = matter)ex/ ocean waves move through water • Electromagnetic waves (EM Waves)the energy moves through disturbances in the electromagnetic field.

  3. WAVE STRUCTURE CREST (peak) AMPLITUDEresting to max peak WAVELENGTH TROUGH

  4. Making a pulse MECHANICAL WAVES require a medium (the material through which the disturbance is moving) to transmit energy travel through & gradually lose energy to that medium • Examples: • water, sound, rope, & spring waves • Mechanical Media: • water, air, rope, spring

  5. Longitudinal, transverse, surface MECHANICAL WAVES Classified by how medium vibrates Pulse = direction of energy transfer Vibration = direction of vibration of medium relative to pulse 3 types:

  6. MECHANICAL WAVES Classified by how medium vibrates Longitudinal Waves: Vibration is in the same direction as wave pulse (parallel to wave pulse) Transverse Waves: Vibration is at 900 (right angles)to wave pulse Surface Waves: Vibration is circular Ex/ Ocean waves; surface waves

  7. TRANVERSE WAVES Vibration is perpendicular to the direction of the motion of the wave • Sideways or up & down • Examples: • S-type earthquake waves • Electromagnetic (EM) or light waves

  8. Rarefraction (expansion) Compression LONGITUDINAL WAVES Vibration is parallel to the direction of the motion of the wave • Back and forth (compression & rarefraction) • Also called compression or pressure wave • Examples: • P-type earthquake waves • Sound waves

  9. Waves describe the Earth P waves move through solids & liquids P waves move through solids & liquids S waves move through solids only!!! Are these MECHANICAL WAVES???? YES!! Seismic waves need a medium (the earth!)

  10. CHARACTERISTICS OF WAVES Waves are described according to their • Amplitudemeasures DISPLACEMENTsize of the disturbance • Wavelength distance of a “repeating unit”Also called a cycle • Velocity vspeed = how fast wave travels

  11. AMPLITUDE • Distance between “rest & crest” or “rest & trough” • Gives indication of “power” or “strength” of wave(magnitude of earthquake = Richter scale) • Does not affect velocity of wave • Determines loudness (sound) or brightness (EM wave)

  12. WAVELENGTH  • Distance between any two repeating points on a wavecrest-crest, trough-trough,expansion-expansion, compression-compression • Determines what colorswe see; what notes we hear (pitch) • Shorter wavelengths have more cycles per minute because they aren’t as long

  13. VELOCITY v • the rate at which the energy travels; speed & direction • Depends on medium • Mechanical waves travel faster through dense mediums • EM Waves are faster through less dense mediums

  14. Frequency ƒ • How oftennumber of wavelengths that pass any point per second • measured in wavelengths/second or cycles/secondHertz (Hz) = number of wavelengths in 1 second • Frequency is related to velocity: v = ƒ 

  15. PERIOD T • How longAmount of time for one wavelength to pass a point • Related inversely to frequency Period= 1 Frequency 1=1T f

  16. Internet resources http://www.glenbrook.k12.il.us/gbssci/Phys/Class/waves/wavestoc.html To test how well you understand go to http://www.physicsclassroom.com/Class/waves/u10l1c.cfm#emmech

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