Longitudinal Waves and Rarefaction:
A longitudinal wave is a wave in which the particles of the medium vibrate in the same direction as the wave itself. It consists of compressions and rarefactions, which are regions of high and low pressure respectively.
The rarefaction is a part of the longitudinal wave where the particles of the medium are farther apart than their normal positions. Let's explore this concept in more detail:
Rarefaction:
- Rarefaction is a region in a longitudinal wave where the particles of the medium are spread apart.
- It is the opposite of compression, where particles are close together.
- In a rarefaction, the particles have moved away from their equilibrium position.
- The density of the medium in a rarefaction is lower than its normal density.
- It is represented by a trough-like shape in a waveform.
Comparison with other wave components:
- Trough: A trough is a low point on a transverse wave, not a longitudinal wave. It is not the correct answer in this case.
- Compression: A compression is a region in a longitudinal wave where the particles of the medium are close together. It is the opposite of rarefaction.
- Crest: A crest is a high point on a transverse wave, not a longitudinal wave. It is not the correct answer in this case.
Conclusion:
The correct answer is A: Rarefaction. In a longitudinal wave, rarefaction refers to the part where particles are farther apart than their normal positions. It is a region of low pressure and lower density compared to the rest of the medium.

The correct answer is option 'A' - Rarefaction.




- Longitudinal waves are a type of mechanical wave in which the particles of the medium vibrate parallel to the direction of wave propagation.
- These waves are characterized by compressions and rarefactions.
- Examples of longitudinal waves include sound waves and seismic waves.


- In a longitudinal wave, a compression is a region where the particles of the medium are closer together than their normal or rest position.
- The particles in a compression experience high pressure due to the close proximity to each other.
- This region is characterized by high density and high pressure.


- A crest is a term used in transverse waves, not in longitudinal waves.
- In transverse waves, a crest is the highest point of the wave where the displacement of the particles is maximum.


- Similarly, a trough is also a term used in transverse waves, not in longitudinal waves.
- In transverse waves, a trough is the lowest point of the wave where the displacement of the particles is minimum.


- In a longitudinal wave, a rarefaction is a region where the particles of the medium are farther away from each other than their normal or rest position.
- The particles in a rarefaction experience low pressure due to the increased distance between them.
- This region is characterized by low density and low pressure.
- It is the opposite of a compression.


- In summary, in a longitudinal wave, the part of the wave where the particles of the medium are farther away from each other than their normal position is called a rarefaction.
- Rarefactions are regions of low density and low pressure in the wave.
- Option 'A' - Rarefaction is the correct answer.