Question

A screw gauge has a screw having $2$ threads in $1 \,mm$. The circular scale has $50$ divisions. Find the diameter of wire, if the main scale shows $6^{th}$ division and the vernier reads $46$.

• A. $6.46\, mm$
• B. $3.46\, mm$
• C. $6.54\, mm$
• D. $3.04\, mm$

Answer 1

Answer: (B)

Least count $=\frac{Pitch}{Number\,of\,divisons}=\frac{0.5}{50}=0.01\,mm$
Diameter of wire $= 6 \times 0.5 + 46 \times 0.01 = 3.46\, mm$