JEEPhysics

Experimental Physics

1 JEE Physics previous year questions on Experimental Physics — options free on every question; 1 include the answer & explanation free, the rest unlock with PYQ Pass.

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PYQ

One main scale division of a vernier calipers is ' a ' cm and \({n}^{\text{th }}\) division of the vernier scale coincide with \((n-1{)}^{\text{th }}\) division of the main scale. The least count of the calipers (in mm ) is:

a

\(\frac{10na}{n-1}\)

b

\(\frac{10a}{n-1}\)

c

\(\frac{10a}{n}\)

d

\(\left(\frac{n-1}{10n}\right)a\)

✓ Correct answer: c)

\(\frac{10a}{n}\)

Explanation

\[(n-1) M S D=n V S D \Rightarrow V S D=\frac{n-1}{n}(M S D)\]

Now, L.C \(=[1 \mathrm{MSD}-1 \mathrm{VSD}] \mathrm{cm}\)
\[\begin{aligned}& =a-\frac{n-1}{n} a=\frac{a}{n} \mathrm{~cm} \\& =\left(\frac{10 a}{n}\right) \mathrm{mm}\end{aligned}\]

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