Question

A spherometer has 20 threads per cm. Its circular scale has 100 divisions. Find the least count of spherometer –

• A. 5 mm
• B. 50 mm
• C. 0.5 mm
• D. 0.05 mm

Answer 1

Answer: (A)

5 mm

Answer 2

Least count

= $\frac { \text { Pitch } } { \text { number of division on circularscale } }$

= $\frac { 0.1 } { 2 }$ = 0.5 × 10^–3 cm