JEE Main & Advanced Physics Mathematical Tools, Units & Dimensions JEE PYQ - Mathematical Tools Units and Dimensions

  • question_answer
    N divisions on the main scale of a vernier caliper coincide with (N + 1) divisions of the vernier scale. If each division of main scale is 'a' units then the least count of the instrument is [JEE ONLINE 19-05-2012]

    A) a

    B) \[\frac{a}{N}\]  

    C) \[\frac{N}{N+1}\times a\]

    D) \[\frac{a}{N+1}\]

    Correct Answer: D

    Solution :

    [d] No of divisions on main scale = N
    No of divisions on vernier scale = N + 1
    size of main scale division = a
    Let size of vernier scale division be b then we 
    have
    \[aN=b(N+1)\Rightarrow b=\frac{aN}{N+1}\]
    Least count is \[a-b=a-\frac{aN}{N+1}\]
                \[=a\left[ \frac{N+1-N}{N+1} \right]=\frac{a}{N+1}\]


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