Question

A student measured the diameter of a small steel ball using a screw gauge of least count $0.001\, cm$. The main scale reading is $5\, mm$ and zero of circular scale division coincides with $25$ divisions above the reference level. If screw gauge has a zero error of - $0.004\, cm$, the correct diameter of the ball is

• A. 0.529 cm
• B. 0.521 cm
• C. 0.053 cm
• D. 0.525 cm

Answer 1

Answer: (A)

0.529 cm

Answer 2

Diameter of the ball
$= MSR + CSR \times$ (Least count) - Zero error
$=0.5 \,cm +25 \times 0.001-(-0.004)$
$=0.5+0.025+0.004$
$=0.529\, cm$