Application of Ultrasonic waves SONAR is a device which stands for sound navigation and ranging. It is based on the principle of echo sounding. In this acoustical technique highfrequency ultrasonic wave are used. When ultrasonic waves are transmitted through water , gets reflected by the object under water. The change in frequency of the echo signals due to the Doppler effect helps us to determine the velocity , distance and the direction of object. In the absence of an obstacle the ultrasonic waves do not get reflected to the receiving transducer. But in the presence of an obstacle the ultrasonic waves get reflected and are picked up by the receiving transducer. Knowing the velocity of ultrasound and the elapsed time, the distance of the object can be determined. Using SONAR, the distance and direction of submarines, depth of sea, depth of rocks in the sea, the shoul of fish in the sea, etc., can be determined. 1. Determinati of Depth of Sea The ultraso
Determination of Velocity of Ultrasonic waves Principle When ultrasonic waves passed through transparent liquid medium in a container, the waves get reflected. These reflected waves are called echos. The direct and reflected waves superimpose to form the stationary wave pattern. These waves give rise to a periodic vibration in the density of the liquid. The change density of the liquid in turn leads to vibration in the refractive index of the liquid. The density of the liquid would be maximum at nodal planes, while at the antinodal planes, it would be minimum. Such a liquid column subjected ultrasonic waves behaves like a grating. Under this condition, if a parallel beam of light is passed through the liquid at right angles to the waves, the liquid acts as a diffraction grating. Such a grating is known as acoustic grating. Experiment Thee experimental arrangement is shown in figure. There is a glass vessel containing tho liquid with a reflector fixed within the