Experimental Physics

JEE Main level, single correct, medium

28 of 70

Question 28 of 70

A travelling microscope has 2020 divisions per cmcm on the main scale while its Vernier scale has total 5050 divisions and 2525 Vernier scale divisions are equal to 2424 main scale divisions, what is the least count of the travelling microscope ?

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Answer: (C) 0.002cm0.002cm

One main scale division MSD=120cmMSD=\dfrac{1}{20}cm
One vernier scale division VSD=2425MSD=2425×120cmVSD=\dfrac{24}{25}MSD=\dfrac{24}{25}\times \dfrac{1}{20}cm
∴∴ Least count LC=MSD−VSD=120(1−2425)cmLC=MSD-VSD=\dfrac{1}{20}\left(1-\dfrac{24}{25}\right)cm
=120×125=1500=0.002cm=\dfrac{1}{20}\times \dfrac{1}{25}=\dfrac{1}{500}=0.002cm
=0.002cm=0.002cm

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