Question

how does the sonar works on the princple of reflectuion of sound

Answer 1

The reflection of sound is similar to the reflection of light as it follows the laws of reflections, where the angle of incidence is equal to the angle of reflection and the incident sound, the reflected sound and the normal lie in the same plane. Sound bounces off the surface of solid or a liquid like a billiard ball bounces off the sides of the table. In order for reflection of sound to occur, the surface can be either rough or polished and of considerably large size.
Laws of Reflection of Sound

The angle of incidence is always equal to the angle of reflection.The incident sound wave, the reflected wave and the normal at the point of incidence are in the same plane.

Applications of reflection of sound

Echo

The sound heard after reflections from a rigid surface such as a cliff or a wall is called echo creating a persistence of sound even after the source of sound has stopped vibrating. Echo is used by bats and dolphins to detect obstacles or navigate.  The same principle is used in SONAR, sound navigation and ranging technique, used in oceanographic studies. SONAR is used for the detection and location of unseen underwater objects, such as submerged submarine, sunken ships and ice bergs. In SONAR, ultrasonic waves are sent in all directions from the ship and the received signal is analyzed.