Question

A screw gauge with a pitch of $0.3mm$ and a circular scale with $100$ divisions is used to measure the thickness of a thin sheet of steel. What is the thickness of the sheet if main scale reading is $1mm$ and the $30^{th}$ division coincides with the main scale line. (There is no zero error)?

• A. $1.9mm$
• B. $1.09mm$
• C. $1.1mm$
• D. $1.99mm$

Answer 1

Answer: (B)

Least count $=\frac{pitch}{\text{no.of division on circular scale}}=\frac{0 . 3 mm}{100}=0.003mm$
Measured value $=1mm+30\times 0.003=1.09mm$