Question

SONAR works on the principle of:
A) Reflection of sound waves
B) Momentum of sound waves
C) Energy of sound waves
D) Refraction of sound waves

Answer 1

Hint: SONAR is the acronym for SOund Navigation And Ranging. It is primarily used in ships. Some animals like bats and whales also employ the working principle of SONAR for their survival. The working of a SONAR is based on the generation of an echo of a sound.

Complete step by step answer:
Try to explain the concept of an echo to get an idea of the working principle of SONAR.
Sometimes, in certain places, when we say something, we hear our own voice coming back to us or in other words, we hear the reflection of our own sound. This phenomenon is referred to as an echo. It is like a second sound but with less amplitude. A SONAR works on the same principle as that of an echo. Echoes are produced when a sound wave is reflected back on hitting an obstacle in its path. The reflected sound wave will then travel back to the source. The figure given below depicts the process involved in the working of the SONAR.
So we can conclude that SONAR works on the principle of reflection of sound waves.

Hence the correct option is A.

Additional information: SONAR finds many applications. It is actively used for underwater communications in ships and submarines. It is also used to detect cancer cells and cysts in a body. And it is used in the military to locate enemy vessels and torpedo. Two types of SONAR exist – active SONAR and passive SONAR. Active SONAR can send and receive acoustic signals whereas passive SONAR can only listen to the signals that travel towards it.

Note: SONAR calculates the distance between the obstacle and the source by recording the difference in the time taken by the original sound wave to be sent and the time taken for the reflected wave to be received at the source. Bats and whales use the same principle to determine if there are any obstacles in their path. Since sound needs a medium to propagate, SONAR cannot function in a vacuum.