Question

with the help of an activity show that sound cannot travel in vacuum.(a)give three uses of ultrasound. (b)what is SONAR?​

Answer 1

The experiment is done by placing an electrical bell in the bell jar. However, the sound is not audible to our ears because of the vacuum inside the jar. This demonstrates that the sound wave cannot travel through vacuum. That is, a sound wave needs a material medium for its propagation. A vacuum is an area without any air, like space. So sound cannot travel through space because there is no matter for the vibrations to work on it.

Uses of Ultrasound

• It is used to get image of heart.  
• It is used to clean hard to reach parts of different machine parts.
• It is used to detect flaws in any metal objects.
• It is used to break stoned in gall bladder.
• It is used for ultrasonography process.

What is SONAR?

SONAR is a technique that uses sound propagation to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.

• A system for the detection of objects under water by emitting sound pulses and detecting or measuring their return after being reflected.

• The method of echolocation used in air or water by animals such as whales and bats.