Test: Production And Propagation Of Sound - Class 9

It vibrates, which, in turn, causes the air around it to vibrate. The vibration of air causes your eardrum to vibrate in tune with the vibrating air. This is interpreted by your brain as sound.

Sound needs a medium to be transmitted thus a person on the moon cannot hear another person on the moon. This is because there is no air on the moon and it is a vaccum thus there is no medium for sound waves to travel.

The motion of the particles of a medium when a sound wave is passing through it is oscillatory because the particles move forward set the neighbouring particle into motion and then come back to it's original position. The particles move to and fro which is also called oscillatory motion.

A wave can be thought of as a disturbance or oscillation that travels through space-time, accompanied by a transfer of energy. The direction a wave propagates is perpendicular to the direction it oscillates for transverse waves. A wave does not move mass in the direction of propagation; it transfers energy.

Sound is produced when something vibrates. The vibrating body causes the medium (water, air, etc.) around it to vibrate. Vibrations in air are called traveling longitudinal waves, which we can hear.

Sound waves in air comprise of compressions and rarefactions. These compressions and rarefactions vibrate in a direction parallel to the direction of wave propagation, which is the fundamental prperty of a longitudinal wave. Hence, sound waves in air are longitudinal waves.

If the particles of the medium vibrate in a direction perpendicular to the direction of propagation of the wave, it is called a transverse wave. In transverse waves, the particle movement is perpendicular to the direction of wave propagation.

Sound cannot travel through vacuum. It needs a material medium to propagate.

Sound have the mechanical waves because it required to move their medium (solid, liquid or gas)and sound always move in medium.

It is used in SONAR (Sound Navigation and Ranging) to determine the depth of the sea and to locate underwater objects like sunken ships, hills, icebergs, etc. The formula used is:

2d = v × t

Where, d = depth of the sea

v = velocity of the sound in the medium

t = time interval between transmission and reception of the ultrasounds.

It is used to detect cracks and flaws in metal blocks.