The ultrasonic waves also known as ultrasound were first produced by Galton. The frequency of these waves is more than 20,000 Hz. In the beginning these waves were called as Galton’s whistle. Now a days the ultrasonic waves of different frequencies can be produced by vibrating quartz crystal. The wavelength of ultrasonic waves in water is less than 1.6 cm.
The wavelength of the ultrasonic waves is quite small or the frequency of these waves is very high that is why the energy associated with them is very high. These waves can bring such miracles which ordinary sound waves can not do.
These waves are used to measure the depth of the ocean bed and to detect icebergs, underwater rocks, big fish and submarines. For this purpose signals of ultrasonic waves are transmitted into the ocean water which gets reflected from these objects. The reflected waves are received and the time taken by the transmitted and the reflected waves is measured. Using the velocity of ultrasonic waves in water the distance of these objects is measured. This instrument is called the sonar and it is of great use in the battlefield. These waves are also used to detect and locate the faults in thick metal sheets.
Ultrasonic waves are also being used to clear dust and coal particles on fogy days at airports. These waves are also used to clean the complex parts of the machines. They are also used to kill small insects.
Nowadays, ultrasonic waves are finding large scale applications is medicine and surgery. Tumors in the body can located with the help of these waves without any operation. The sex of a child in the womb can be known by ultrasonic scan. These waves are also being used for the extraction of teeth. After three months of pregnancy, we can also detect whether the baby is a boy or girl with the help of ultrasonic scan or popularly known as ultrasound. Even various heart aliments, stones in the kidneys or gall bladder, etc. can be detected from ultrasound. Hence, these ultrasonic waves are a boon for medical science. These waves are also being used to diagnose the stomach ailments. They are not harmful to the body.
The valuable optical components are cleaned by ultrasonic waves. Ultrasonic machines are being used to drill holes in glass and ceramics. These waves, in fact are very useful for us.