Sound Waves

Sound Waves

1. Explanation

   • vibrations
   • air in front
     • compresses
     • stretches
   • movements
     • out thru air
       • waves
   • eardrums
     • vibrate
       • hear sound
   • Longitudinal
     • vibrate
       • back
       • forth
   • stretches
     • rarefactions
     • air pressure lower than normal

2. Diffraction

   • Bend round
     • obstacles
   • hear around corners
   • greater
     • longer wavelength

3. speed of sound

   • depends on
     • temperature of air
   • faster thru
     • hot air
       • than cold air
   • change causes
     • refraction
       • change in
         • direction of travel
   • diff thru
     • diff materials

4. Radar

   • works like echo sounder
   • microwaves
     • by air craft
       • sent out
       • reflected

5. Frequency

   • No. of periodic oscillations
     • 1 sec

6. Amplitude and loudness

   • greater amplitude
     • louder sound
   • speed
     • freq. x wavelength
   • higher frequency
     • shorter wavelength