Physical World Units And Measurements Ques 45

45. In a vernier calliper $N$ divisions of vernier scale coincides with $(N-1)$ divisions of main scale (in which length of one division is $1 $ $mm$ ). The least count of the instrument should be

[1994]

(a) $N$

(b) $N-1$

(c) $1 / 10$ $ N$

(d) $1 / N-1$

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Answer:

Correct Answer: 45.(c)

Solution:

  1. (c) Least count = 1MSD - 1 VSD

$=1 $ $MSD-(\frac{N-1}{N})$ $ MSD$

$=\frac{1}{N} $ $MSD=\frac{1}{N} \times \frac{1}{10} $ $cm=\frac{1}{10 N}$

Smaller value of the least count, higher is the accuracy of measurement. Accuracy of measurement is higher when number of significant figure after the decimal in measurement is larger.