Echo is _________ of the sound.

The reflection of sound in a closed surface is called _______.

• Amplification refers to the increase of the amplitude or loudness of sound.
• The repetition of a sound that is caused by the reflection of sound wave in large spaces is called an echo.

Which of the below is used to amplify sound?

Units to measure sound:

• The unit of power is watt.
• The unit of force is newton.
• The unit of work is Joule.

SONAR is used in _______

A sonar can detect the enemy ship using
_________ .

Distance can be measured in___________.

• The SI unit of time is Second.
• The SI unit of pressure is Pascal.
• The SI unit of force is Newton.

Music is heard from a vehicle's horn.

The SI unit of measurement of velocity is kg/s.

A guitar can produce __________.

Sound from a speaker undergoes an echo to reach the source back from a mountain located at a distance of 340 m from the source. The total time taken by the sound to cover this distance is 2 s. The speed of sound is ___ m/s.

After echo, the total distance travelled = 2d

Decreasing amplitude of a sound wave decreases the _______.

Cinema theatres are designed for the sound to _______.

To make a sound louder, the sound should be _______.

If a sound travels a distance of 100 m in 2 s, its velocity is ____ m/s.

The horn of a vehicle is based on ___________ of sound.

• A megaphone works on the principle of multiple reflections of sound.