Waves that cannot be polarised are

Options

A. Light waves
B. Electromagnetic waves
C. Transverse waves
D. Longitudinal waves

Answer

To determine which waves cannot be polarized, we need to understand the nature of different types of waves and the concept of polarization.

### Step-by-Step Solution:

1. **Identify Types of Waves**:
- Waves can be classified into two main types: transverse waves and longitudinal waves.
- **Transverse Waves**: In these waves, the particle motion is perpendicular to the direction of wave propagation. Examples include light waves and electromagnetic waves.
- **Longitudinal Waves**: In these waves, the particle motion is parallel to the direction of wave propagation. An example is sound waves.

2. **Understanding Polarization**:
- **Polarization** is the process of transforming unpolarized waves into polarized waves.
- Polarized waves have their vibrations in a single plane, while unpolarized waves have vibrations in multiple planes.

3. **Analyzing Wave Types for Polarization**:
- **Transverse Waves**: These can be polarized because their vibrations can be restricted to a single plane. Light waves and electromagnetic waves fall into this category.
- **Longitudinal Waves**: These cannot be polarized because the particle motion is in the same direction as the wave motion, meaning they cannot be restricted to a single plane.

4. **Conclusion**:
- From the options given (light waves, electromagnetic waves, transverse waves, and longitudinal waves), the type of waves that cannot be polarized is **longitudinal waves**.

### Final Answer:
**Longitudinal waves cannot be polarized.**

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