In a travelling microscope, 300 main-scale divisions are equal to 15 cm. The vernier has 25 divisions equal to 24 main-scale divisions. The least count of the microscope is:
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Question

In a travelling microscope, 300 main-scale divisions are equal to 15 cm. The vernier has 25 divisions equal to 24 main-scale divisions. The least count of the microscope is:

G1 Physics · Accepted Answer

One main-scale division is 1 MSD = 15/300 = 0.05 cm. Given 25 VSD = 24 MSD, 1 VSD = (24/25)MSD = (24/25)(0.05) = 0.048 cm. For a direct vernier, Least count = 1 MSD - 1 VSD = 0.05-0.048 = 0.002 cm. Correct option: A.