Home › MCQs › EEJ MAIN Physics › Question #7042
Back to Questions
EEJ MAIN Physics QUESTION #7042
Question 1
The main scale of a screw gauge has a least count of $1 \text{ mm}$. How many circular scale divisions are needed at minimum to measure a $5 \ \mu\text{m}$ diameter wire?
  • $50$
  • $200$✔️
  • $100$
  • $500$
Correct Answer Explanation

Least Count ($LC$) of a screw gauge is given by: $LC = \frac{\text{Pitch}}{\text{Number of divisions (N)}}$.

Given $LC = 5 \ \mu\text{m} = 5 \times 10^{-6} \text{ m}$ and Pitch $= 1 \text{ mm} = 10^{-3} \text{ m}$.

$N = \frac{10^{-3}}{5 \times 10^{-6}} = \frac{1000}{5} = 200$.