Sound wave in air cannot be polarised because

Options

A. their speed is small
B. they require medium
C. these are longitudinal
D. their speed is temperature dependent

Explanation

To solve the question "Sound wave in air cannot be polarised because," we need to understand the nature of sound waves and the concept of polarization.

### Step-by-Step Solution:

1. **Identify the Type of Wave**:
- Sound waves are classified as longitudinal waves. In longitudinal waves, the particle displacement is parallel to the direction of wave propagation.

2. **Understanding Polarization**:
- Polarization is a phenomenon that occurs only in transverse waves. In transverse waves, the particle displacement is perpendicular to the direction of wave propagation. This allows for the alignment of the wave's oscillations in a particular direction.

3. **Reasoning**:
- Since sound waves are longitudinal, they do not have a perpendicular displacement component that can be aligned. Therefore, they cannot be polarized.

4. **Conclusion**:
- The reason sound waves in air cannot be polarized is that they are longitudinal waves, and only transverse waves can exhibit polarization.

### Final Answer:
Sound waves in air cannot be polarised because they are longitudinal waves, and polarization only occurs in transverse waves.

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