SOUND - 8th Class

  1. A vibrating body produces sound.
  2. Sound has energy
  3. Sounds are produced by vibrating bodies and the air that passes through orifices of the instruments.
  4. Sound needs a medium to propagate.
  5. The to and fro motion of a body from its mean position is known as one vibration.
  6. The maximum displacement of vibrating body from its mean position is called as amplitude.
  7. The number of vibrations per second is called as frequency.
  8. The shrillness of a sound is known as pitch.
  9. The pitch of the sound depends upon its frequency.
  10. Normal sound consists of mixed frequencies.
  11. The sounds which are pleasant to hear are called as music. Music is a combination of sounds that are produced in an order and pleasant to hear.
  12. The sounds which are unpleasant to hear are called as noise.
  13. The sounds that a normal human being can hear are called as audible sounds.
  14. The sounds that a normal human being cannot hear are called inaudible sounds.
  15. Frequency of the audible sounds ranges from 20 Hertz (20 vibrations/sec) to 20000 Hertz(20000 vibrations/sec). 



 

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