Choose the correct alternative

Options

A. When plane polarised light passes through polaroid, it changes it changes its nature to linearly polarised
B. Refracted light, when light is incident at Brewster angle, in linearly polarised
C. Polarised light can be produced by scattering through `pi/2` in earth's atmosphere
D. Natural light from sun is polarised

Answer

To solve the question, we need to analyze each option provided and determine which one is correct regarding the properties of polarized light.

### Step-by-Step Solution:

1. **Understanding Option 1**:
- The statement claims that when plane polarized light is passed through a Polaroid, it changes its nature to linearly polarized light.
- **Analysis**: This is incorrect. Plane polarized light remains plane polarized after passing through a Polaroid. The correct terminology is that Polaroid filters produce plane polarized light from unpolarized light, not linearly polarized light.
- **Conclusion**: Option 1 is incorrect.

2. **Understanding Option 2**:
- The statement mentions that when light is incident at Brewster's Angle, the reflected ray is plane-polarized.
- **Analysis**: This is also incorrect as it refers to the reflected light being linearly polarized, which is a specific case of plane polarization. However, the terminology used here is misleading.
- **Conclusion**: Option 2 is incorrect.

3. **Understanding Option 3**:
- The statement claims that plane-polarized light can be produced by scattering through π/2 in Earth's atmosphere.
- **Analysis**: This is correct. When light scatters at an angle of π/2 (90 degrees), it results in polarized light due to the scattering process, which is a known phenomenon in atmospheric physics.
- **Conclusion**: Option 3 is correct.

4. **Understanding Option 4**:
- The statement asserts that natural light is polarized.
- **Analysis**: This is incorrect. Natural light is typically unpolarized, meaning it propagates in multiple planes and does not have a preferred direction of polarization.
- **Conclusion**: Option 4 is incorrect.

### Final Answer:
The correct alternative is **Option 3**.

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