Q79 / 90 · JEE Main 2022 (29 Jul Shift 1) · Physics

A travelling microscope has $20$ divisions per $cm$ on the main scale while its Vernier scale has total $50$ divisions and $25$ Vernier scale divisions are equal to $24$ main scale divisions, what is the least count of the travelling microscope ?

A
$0.001 cm$
B
$0.002 mm$
Correct answer
C
$0.002 cm$
D
$0.005 cm$

Solution

One main scale division $MSD = \frac{1}{20} cm$
One vernier scale division $VSD = \frac{24}{25} MSD = \frac{24}{25} \times \frac{1}{20} cm$
$∴$ Least count $LC = MSD - VSD = \frac{1}{20} (1 - \frac{24}{25}) cm$
$= \frac{1}{20} \times \frac{1}{25} = \frac{1}{500} = 0.002 cm$
$= 0.002 cm$

Hence, the correct answer is option: 'C'.

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A travelling microscope has 20 divisions per cm on the main scale while its Vernier scale has total 50 divisions and 25 Vernier scale divisions are equal to 24 main scale divisions, what is the least count of the travelling microscope ?

Solution

Relevant Questions

A travelling microscope has $20$ divisions per $cm$ on the main scale while its Vernier scale has total $50$ divisions and $25$ Vernier scale divisions are equal to $24$ main scale divisions, what is the least count of the travelling microscope ?