A screw gauge has 50 divisions on its circular scale and its screw moves by 1 mm on turning it by two rotations. When the flat end of the screw is in contact with the stud, the zero of circular scale lies below the base line and 4th division of circular scale is in line with the base line. Find the zero error, of the screw gauge.

Explanation

To find the zero error of the screw gauge, we will follow these steps:

### Step 1: Determine the Pitch of the Screw Gauge
The pitch of the screw gauge can be calculated using the formula:
\[ \text{Pitch} = \frac{\text{Distance moved}}{\text{Number of rotations}} \]
Given that the screw moves 1 mm for 2 rotations, we can calculate the pitch as follows:
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