Ultrasonic Interferometer

1) What are ultrasonic waves?
Ans: Ultrasonic waves are sound waves, whose frequencies are greater than 20KHz. Their wavelength is less than 1.65cm. They exhibit all the properties of sound waves and some additional properties.

2) What are the properties of ultrasonic waves?
Ans:
i)Ultrasonic waves are longitudinal waves of high frequency(greater than 20KHz). Owing to their short wave length they can travel long distances as a sharp beam.
ii) They undergo reflection and refraction.
iii) They produce heating effect, mechanical effect & chemical effect.
iv) They produce biological effect. Animals such as frogs and rats are killed when subjected to ultrasonic waves.


3) How are ultrasonic are produced?
Ans: Ultrasonic are produced by
i) Galton's whistle.
ii) Magnetostriction oscillator
iii) Piezo-electric generator

Galton'd whistle is primarily a mechanical device based on the principle of resonance of air column. It can produce ultrasonic waves about 30KHz.

A magnetostriction oscillator is based on the property of magnetostriction exhibited by ferromagnetic materials. It can produce ultrasonic waves of 25KHz.

Piezo-electic oscillator is also an electrical device, which makes use of the piezo-electric property of quartz. It generators ultrasonic waves of high frequencies.