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Question: Answered & Verified by Expert
In an experiment the angles are required to be measured using an instrument. 29 divisions of the main scale exactly coincide with the 30 divisions of the vernier scale. If the smallest division of the main scale is half-a-degree $\left(=0.5^{\circ}\right)$, then the least count of the instrument is
PhysicsExperimental PhysicsJEE MainJEE Main 2009
Options:
  • A
    one minute
  • B
    half minute
  • C
    one degree
  • D
    half degree
Solution:
1635 Upvotes Verified Answer
The correct answer is:
one minute
$$
\text { Least count }=\frac{\text { value of main scale division }}{\text { No of divisions on vernier scale }}=\frac{1}{30} \mathrm{MSD}=\frac{1}{30} \times \frac{1}{2}^{\circ}=\frac{1}{60}^{\circ}=1 \text { minute }
$$

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