Assertion A diverging lens (in air) cannot be made more diverging whatever be the medium we choose completely immerse the lens.
Reason The minimum refractive index of any medium is 1.

Options

A. (a) If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B. (b) If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
C. (c) If Assertion is true but Reason is false.
D. (d) If Assertion is false but Reason is true.

Explanation

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

### Step 1: Understand the Assertion
The assertion states that "a diverging lens (in air) cannot be made more diverging whatever be the medium we choose to completely immerse the lens." A diverging lens is typically a concave lens, which has a negative focal length.

### Step 2: Analyze the Focal Length of a Diverging Lens
The focal length (f) of a lens is given by the lens maker's formula:
\[ \frac{1}{f} = (\mu - 1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right) \]
where:
- \( \mu \) is the refractive index of the medium in which the lens is placed,
- \( R_1 \) and \( R_2 \) are the radii of curvature of the lens surfaces.

For a diverging lens:
- \( R_1 \) is negative (since it is concave),
- \( R_2 \) is positive.

### Step 3: Effect of Immersing the Lens in Different Mediums
When the lens is immersed in a medium with a refractive index \( \mu \):
- If \( \mu \) is 1 (air), the lens behaves normally.
- If \( \mu \) increases (for example, immersing in water or glass), the term \( (\mu - 1) \) becomes positive, which affects the focal length.

### Step 4: Determine the Nature of the Focal Length
As \( \mu \) increases, the term \( (\mu - 1) \) increases, making the value of \( \frac{1}{f} \) more positive. This means that the focal length \( f \) becomes less negative (or more positive), indicating that the lens is becoming less diverging or even converging.

### Step 5: Conclusion on the Assertion
Thus, the assertion is correct because a diverging lens cannot be made more diverging in any medium, as immersing it in a medium with a refractive index greater than 1 will lead to a less diverging (or converging) effect.

### Step 6: Analyze the Reason
The reason states that "the minimum refractive index of any medium is 1." This is also correct because the refractive index of air is approximately 1, and no medium can have a refractive index less than 1.

### Final Conclusion
Both the assertion and the reason are true, and the reason correctly supports the assertion.

### Answer:
Both the assertion and reason are true, and the reason supports the assertion.

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