Which of the following statements is/are correct regarding the sound waves 1) Sound waves cannot travel through a vacuum. 2) The particles oscillate up and down about their mean position as the wave travels. 3) In a given medium under the same physical conditions, the speed of sound changes drastically with a change in frequency. Select the correct answer using the code given below.?

Option 1 : 1 only

CONCEPT:

• Sound: A sound is a form of energy that produces the sensation of hearing in our ears.
  • When a source of sound vibrates, it creates a disturbance in the medium. The particles of the medium vibrate in their mean position to transfer this disturbance.
  • So, the particles move forward and backwards about their mean position, creating regions of compression and rarefaction.
  • Hence, a sound wave travels in a series of compression and rarefactions.
  • Due to the nature of the transfer of sound energy, sound always requires a medium to propagate.

The correct answer is 1 only.

EXPLANATION:

• Sound is a mechanical wave and needs a material medium like air, water, steel, etc. for its propagation.
• It cannot travel through a vacuum. Hence statement 1^st is correct.
• In these waves, the individual particles of the medium move in a direction parallel to the direction of propagation of the disturbance.
• The particles do not move from one place to another but they simply oscillate back and forth about their position of rest.
• This is exactly how a sound wave propagates, hence sound waves are longitudinal waves. 
• Hence statement 2^nd is incorrect.
• The speed of sound remains almost the same for all frequencies in a given medium under the same physical conditions. Hence statement 3rd is incorrect.

Hence option 1 is correct.