For the determination of the refractive index of a glass slab, a travelling microscope is used whose main scale contains 300 equal divisions equal to 15 cm. The vernier scale attached to the microscope has 25 divisions equal to 24 divisions of the main scale. The least count (LC) of the travelling microscope is (in cm):

(B) 0.002. 1 MSD = (15)/(300) = 0.05 cm; 1 VSD = (24)/(25) MSD. LC = 1 MSD - 1 VSD = (1)/(25)×0.05 = 0.002 cm

Units and Measurements question for JEE Main (JEE Main 2025 (4 Apr, Shift 2)), with solution

Q 11-01-247JEE MainJEE Main 2025 (4 Apr, Shift 2)Easy

For the determination of the refractive index of a glass slab, a travelling microscope is used whose main scale contains 300 equal divisions equal to $15\ \text{cm}$. The vernier scale attached to the microscope has 25 divisions equal to 24 divisions of the main scale. The least count (LC) of the travelling microscope is (in cm):

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Units and Measurements question for JEE Main (JEE Main 2025 (4 Apr, Shift 2)), with solution

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