In a complete rotation, spindle of a screw gauge advances by `(1)/(2)mm`. There are `50` divisions on circular scale. The main scale has `(1)/(2)mm` marks to (is graduated to `(1)/(2)mm`)
If a wire is put between the jaws, `3` main scale divisions are clearly visible, and `20th` division of circular scale coincides with reference line. Find diameter of wire in correct significant figures.

Explanation

To find the diameter of the wire using the screw gauge, we can follow these steps:

### Step 1: Understand the Measurements
- The screw gauge advances by \( \frac{1}{2} \, \text{mm} \) for one complete rotation.
- There are 50 divisions on the circular scale.
- The main scale is graduated to \( \frac{1}{2} \, \text{mm} \).

### Step 2: Calculate the Value of One Circular Scale Division
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