Maharashtra State PSC Model Paper 3

The correct answer is Ultrasonic.

• The sound produced by a bat is Ultrasonic.

• The longitudinal mechanical waves having frequencies greater than 20000 Hz are called ultrasonic waves. 
• Applications of Ultrasonic Waves:
  • For sending signals.
  • For measuring the depth of the sea.
  • For cleaning clothes, aeroplanes and machinery parts of clocks.
  • For removing lamp-shoot from the chimney of factories.
  • In sterilising of a liquid.
  • In ultrasonography.