The human ear can detect sound waves of frequency lying in the range 20 to 20,000 Hz. Sound waves having frequencies greater than 20,000 Hz are known as ultrasonics. Ultrasonic waves, because of high frequencies, have a large energy as E= hv and therefore a high enetrating power. Due to this property, they find wide applications in processes such as flaw detection,
drilling and soldering etc. Recently, they have also been employed for the detection of various
diseases in the human body.
Ultrasonic waves are sound waves in nature and can therefore undergo processes such as Reflection, refraction and absorption. It may be pointed out that ultrasonic waves travels with the same speed as sound waves but have a greater frequency, or smaller wavelength than them.
Some other properties of ultrasonic waves are as:
1. The speed of propagation of ultrasonic waves increases with increase in frequency.
2. The wavelength of the waves is very small and the waves exhibit negligible diffraction
3. They can travel over long distances as a highly directional beam and without
appreciable loss of energy.
4. They produce cavitation effects in liquids.