General Physics Ques 25
- A student measured the length of a rod and wrote it as $3.50 \mathrm{~cm}$. Which instrument did he use to measure it?
(2014 Main)
(a) A meter scale
(b) A vernier caliper where the 10 divisions in vernier scale matches with 9 divisions in main scale and main scale has 10 divisions in $1 \mathrm{~cm}$
(c) A screw gauge having 100 divisions in the circular scale and pitch as $1 \mathrm{~mm}$.
(d) A screw gauge having 50 divisions in the circular scale
Show Answer
Answer:
Correct Answer: 25.( b )
Solution:
- If student measures $3.50 \mathrm{~cm}$, it means that there is an uncertainly of order $0.01 \mathrm{~cm}$.
For vernier scale with $1 \mathrm{MSD}=\frac{1}{10} \mathrm{~cm}$ and $ 9 \mathrm{MSD}=10 \mathrm{VSD} $
$\mathrm{LC}$ of vernier caliper $=1 \mathrm{MSD}-1 \mathrm{VSD}$
$ =\frac{1}{10}\left(1-\frac{9}{10}\right)=\frac{1}{100} \mathrm{~cm}=0.01 \mathrm{~cm} $
BETA
