Which of the following shows the bending of light from rarer (R) into denser (D) medium?

Options

A.
B.
C.
D.

Answer

To determine which of the given options shows the bending of light from a rarer medium (R) into a denser medium (D), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Refraction**:
When light travels from a rarer medium to a denser medium, it bends towards the normal. The refractive index (μ) of the rarer medium is less than that of the denser medium.

2. **Identify the Relationship Between Angles**:
According to Snell's Law, the relationship can be expressed as:
\[ μ_r \sin(i) = μ_d \sin(r) \]
where:
- \(μ_r\) = refractive index of the rarer medium
- \(μ_d\) = refractive index of the denser medium
- \(i\) = angle of incidence
- \(r\) = angle of refraction

3. **Analyze the Values of Refractive Indices**:
Since the refractive index of the rarer medium is less than that of the denser medium, we have:
\[ μ_d > μ_r \]
This implies that the term \( \frac{μ_d}{μ_r} > 1 \).

4. **Determine the Relationship Between Angles**:
From Snell's Law rearranged, we can derive:
\[ \sin(r) = \frac{μ_r}{μ_d} \sin(i) \]
Since \( \frac{μ_r}{μ_d} < 1 \), it follows that:
\[ \sin(r) < \sin(i) \]
This indicates that the angle of refraction \(r\) is less than the angle of incidence \(i\):
\[ r < i \]

5. **Conclusion About the Direction of Bending**:
Since \(r < i\), the ray of light bends towards the normal when it enters the denser medium from the rarer medium.

6. **Evaluate the Given Options**:
- **Option 1**: Light travels straight - Incorrect.
- **Option 2**: Light bends towards the normal (i > r) - Correct.
- **Option 3**: Light bends outward (r > i) - Incorrect.
- **Option 4**: Light bends excessively along the interface (r = 90°) - Incorrect.

7. **Final Answer**:
The correct option that shows the bending of light from a rarer medium into a denser medium is **Option 2**.