Question

A student measured the length of a rod and wrote it as $3.50cm$. Which instrument did he use to measure it?

• A. A screw gauge having $100$ division in the circular scale and pitch as $1mm$.
• B. A screw gauge having $50$ divisions in the circular scale and pitch as $1mm$.
• C. A meter scale.
• D. A vernier calliper where the $10$ divisions in vernier scale scale matches with $9$ in main scale and main scale has $10$ divisions in $1cm.$

Answer 1

Answer: (D)

A vernier calliper where the $10$ divisions in vernier scale scale matches with $9$ in main scale and main scale has $10$ divisions in $1cm.$

$Leastcountofverniercalliperis\frac{1}{10}mm=0.1mm=0.01cm$

f student measures $3.50cm$, it means that there is an uncertainly of order $0.01cm$, For vernier scale with $1MSD=1mm$