In a vernier caliper, one main scale division equals 2 mm. The 10th division of the vernier scale coincides with the 9th division of the main scale. What is the least count of the vernier caliper?

0.1 mm
0.05 mm
0.3 mm
0.2 mm

Correct answer: 0.2 mm

Solution

The coincidence condition states that 10 vernier scale divisions (VSD) = 9 main scale divisions (MSD). So 1 VSD = (9/10)*MSD = (9/10)*2 mm = 1.8 mm. Least Count = 1 MSD - 1 VSD = 2 - 1.8 = 0.2 mm.

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