Assertion In Young's double slit experiment, ratio `I_(max)/I_(min)` is infinite
Reason If width of any one of the slits is slightly increased, then this ratio will decrease.

Explanation

To solve the question, we need to analyze the assertion and reason provided regarding Young's double slit experiment.

### Step 1: Understanding the Assertion
The assertion states that in Young's double slit experiment, the ratio of maximum intensity (I_max) to minimum intensity (I_min) is infinite.

In the double slit experiment, the maximum intensity (I_max) occurs when the waves from both slits are in phase, leading to constructive interference. The minimum intensity (I_min) occurs when the waves are out of phase, leading to destructive interference.

Mathematically, the maximum intensity can be expressed as:
\[ I_{max} = 4I_0 \]
where \( I_0 \) is the intensity due to one slit.

The minimum intensity can be expressed as:
\[ I_{min} = 0 \]
when the slits are of equal width and perfectly aligned.

Thus, the ratio:
\[ \frac{I_{max}}{I_{min}} = \frac{4I_0}{0} \]
is indeed infinite.

### Step 2: Understanding the Reason
The reason states that if the width of any one of the slits is slightly increased, then this ratio will decrease.

When the width of one slit is increased, the intensity distribution changes. The increased width results in a greater intensity from that slit, which affects the minimum intensity. The minimum intensity will no longer be zero because the increased intensity from the wider slit will contribute to the overall intensity at points of destructive interference.

As a result, the new minimum intensity (I_min) will be greater than zero, leading to a finite ratio:
\[ \frac{I_{max}}{I_{min}} < \infty \]

### Step 3: Conclusion
Both the assertion and the reason are correct:
- The assertion is correct because the ratio is infinite when both slits are equal.
- The reason is also correct because increasing the width of one slit leads to a non-zero minimum intensity, thus decreasing the ratio.

However, the reason does not directly explain the assertion since the assertion is true only under specific conditions (equal slit widths).

### Final Answer
Both the assertion and reason are correct, but the reason is not the correct explanation of the assertion.