Question

SONAR is based on the principle of
A. Echo
B. Reverberation
C. Resonance
D. Ultrasounds

Answer 1

First let us see what sonar technology is-
Sonar is a method that uses sound propagation (usually underwater, as in submarine navigation) to track, interact with or locate objects, such as other vessels on or under the surface of the sea.
The sonar instrument tests how long it takes to move down the sound wave, strike an item, and then bounce back up.

Complete step by step solution:
An ultrasonic wave reflection occurs when the wave passes between two tissues of distinct acoustic velocities and a fraction of the wave bounces back. This forms one of the main principles of ultrasound imaging as these reflected waves are detected by the ultrasound probe to form the desired image. This very principle is used in sonar technology.
When a sound or signal is mirrored, a reverberation or reverb is produced that allows multiples reflections to build up and then decay as the sound is absorbed by the surfaces of objects in space.
Apart from the target of interest, as active sonar transmits, the signal returns to the receiver from several other sources. Reverberation is considered as a hindrance to SONAR.
Hence, from the above we can conclude that options A and D are correct.

Note:
Pulses of sound waves are sent down through the water by a sonar device. They are reflected back to the surface when these pulses hit objects such as fish, vegetation or the bottom. The sonar instrument measures how long it takes to travel down, hit an object and then reflect back.