Source: Extra Practice

A screw gauge has a pitch of 0.5 mm0.5 \text{ mm} and 50 divisions on its circular scale. What is its least count?

Options

Option A is correct

0.01 mm0.01 \text{ mm}

Option B

0.001 mm0.001 \text{ mm}

Option C

0.1 mm0.1 \text{ mm}

Option D

0.05 mm0.05 \text{ mm}

Explanation

The least count (LC) of a screw gauge is defined as the ratio of its pitch to the total number of divisions on its circular scale. The formula for least count is: LC=PitchNumber of divisions on circular scale\text{LC} = \frac{\text{Pitch}}{\text{Number of divisions on circular scale}} Given: Pitch = 0.5 mm0.5 \text{ mm} Number of divisions on circular scale = 50 Substituting these values: LC=0.5 mm50=5500 mm=1100 mm=0.01 mm\text{LC} = \frac{0.5 \text{ mm}}{50} = \frac{5}{500} \text{ mm} = \frac{1}{100} \text{ mm} = 0.01 \text{ mm}.