Assertion: Water waves in a river are not polarized.
Reason: Water waves are longitudinal in nature.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

To solve the question, we need to analyze the assertion and the reason provided.

**Assertion:** Water waves in a river are not polarized.
**Reason:** Water waves are longitudinal in nature.

### Step-by-Step Solution:

1. **Understanding Wave Types:**
- Waves can be classified into two main types: longitudinal and transverse.
- Longitudinal waves are characterized by oscillations that occur in the same direction as the wave travels (e.g., sound waves).
- Transverse waves have oscillations that occur perpendicular to the direction of wave travel (e.g., light waves, water waves).

2. **Nature of Water Waves:**
- Water waves in a river are primarily transverse waves. The surface of the water oscillates up and down while the wave travels horizontally across the surface.
- This means that the particles of water move in a direction perpendicular to the direction of wave propagation.

3. **Polarization of Waves:**
- Polarization refers to the orientation of oscillations in a wave. For a wave to be polarized, it must have a specific orientation of oscillation.
- Transverse waves can be polarized because their oscillations can be restricted to a particular plane.
- Longitudinal waves cannot be polarized because their oscillations do not have a specific orientation; they involve compressions and rarefactions along the direction of wave travel.

4. **Evaluating the Assertion and Reason:**
- The assertion states that water waves in a river are not polarized. This is true because water waves are primarily transverse and can be polarized.
- The reason states that water waves are longitudinal in nature. This is false because water waves are not longitudinal; they are transverse.

5. **Conclusion:**
- Since the assertion is true but the reason is false, the correct conclusion is that the assertion stands independently of the reason provided.

### Final Answer:
The assertion is true, but the reason is false.

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