The longitudinal waves with frequencies above the audible range are known as of ULTRASONICS.
Ultrasonic have frequency greater than 20,000Hz.
Production of Ultrasonic:
Ultrasonic are produced by vibrating quartz crystals electricity. With the help of this device very high frequency range ultrasonic waves can easily be produced.
Uses of Ultrasonic
• IN MEDICINE
=> Ultrasonic is now widely used as diagnostic therapeutic and surgical tool in medicine.
=> Ultrasonic is preferred over x-rays due to safety.
=> To kill microbes in liquids.
• IN INDUSTRY
=> To find cracks in metal structures.
• IN TECHNOLOGY
=> They are used in echo-depth sounding devices for determining depth of sea.
=> In under water navigation ultrasonic is used instead of RADAR
• IN GENERAL
=> In guidance devices for blind persons.