UNIT-III ULTRASONICS AND APPLICATIONS Introduction-Properties-Production: Magnetostriction effect, magnetostriction generator- piezoelectric effect, piezoelectric generator – Ultrasonic detection- acoustical grating-Applications: Cavitation, cleaning, SONAR,– Non destructive testing: Pulse echo system, through transmission, resonance system- Medical applications: cardiology, neurology, ultrasonic imaging (A, B and TM- Scan). 3.1 INTRODUCTION The sound waves above the frequency of 20000 Hz (20 KHz) are known as ultrasonic waves. Ultrasonic waves are inaudible to humans, because. their high frequencies are unable to vibrate the human ear drum. The ultrasonic waves are high frequency sound waves smaller wave length. Its wave length at room temperature is 0.0175 m. Since they are sound waves, they require a material medium to travel and have most of the properties of sound waves. In addition to this, the ultrasonic waves are having high energy and it h