Vibrations and Waves

Vibrations and Waves

1. Wave description

   • High points=crests
   • low points=troughs
   • Amplitude
     • max. displacement from equilibrium
       • dist. from midpoint to crest/troughs
   • Wavelength
     • dist. from top of one crest to the next
   • frequency
     • amount of vibrations in a unit of time
       • one complete back and forth vibration produces one wave.
         • frequency of vibrating source and waves are the same.
           • sound waves=vibration of objects
             • light waves=vibration of electrons
     • measured in Hertz (Hz)
     • =1/period
       • period=1/frequency

2. Wave Motion

   • Sound, light, earthquakes, radio etc. reach us via wave
   • Energy transported from a vibrating source by a wave is transferred by disturbances in a medium

3. Wave Speed

   • v=λf
     • where λ (lambda)=wavelength

4. Transverse Waves

   • motion of medium at at right angle to direction of wave

5. Longitudinal Waves

   • particles oscillate parallel direction of wave

6. The Doppler Effect

   • Apparent change in frequency due to motion of source
   • Directly porportional to speed of source
   • sound and light
   • for light, apparent increase in frequency=blue shift and decrease=red shift