Assertion:- If your focus is on a point closer to your eyes, the radius of curvature of eye lens decreaes.
Reason:- When rays are to be focused more strongly, a shorter focal length is needed.

Options

A. If both Assertion `&` Reason are True `&` the Reason is a correct explanation of the Assertion.
B. If both Assertion `&` Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion `&` Reason are False.

Answer

To solve the given question, we will analyze both the assertion and the reason step by step.

### Step-by-Step Solution:

1. **Understanding the Assertion:**
- The assertion states that if your focus is on a point closer to your eyes, the radius of curvature of the eye lens decreases.
- This implies that when you look at nearby objects, the eye lens must change its shape to focus the light correctly on the retina.

2. **Understanding the Reason:**
- The reason provided states that when rays are to be focused more strongly, a shorter focal length is needed.
- This is based on the lens formula:
\[ \frac{1}{f} = \frac{1}{v} + \frac{1}{u} \]
- Here, \( f \) is the focal length, \( v \) is the image distance (constant for the retina), and \( u \) is the object distance.

3. **Analyzing the Relationship:**
- When you focus on an object that is closer (decreasing \( u \)), the image must still be formed on the retina (constant \( v \)).
- According to the lens formula, if \( u \) decreases, \( f \) must also decrease to maintain the equality since \( \frac{1}{v} \) is constant.

4. **Radius of Curvature and Focal Length:**
- The focal length \( f \) of a lens is related to its radius of curvature \( R \) by the lens maker's formula:
\[ f = \frac{R}{2(n-1)} \]
- Here, \( n \) is the refractive index of the lens material.
- A decrease in focal length \( f \) implies that the radius of curvature \( R \) must also decrease, as they are inversely related.

5. **Conclusion:**
- Both the assertion and the reason are true. The reason correctly explains why the assertion holds: focusing on closer objects requires a shorter focal length, which is achieved by decreasing the radius of curvature of the eye lens.

### Final Answer:
Both the assertion and reason are true, and the reason is a correct explanation of the assertion.

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