A travelling microscope is used to determine the refractive index of a glass slab. If 40 divisions are there in 1 cm on main scale and 50 Vernier scale divisions are equal to 49 main scale divisions, then least count of the travelling microscope is _____ × 10 - 6 m .

Step-by-step solution

Given here, main scale reading, M S = 1 40   cm And, 50 × V S = 49 × M S Least count of travelling microscope is L C = M S - V S = M S - 49 50   M S = 1 50 × M S = 1 50 × 1 40   cm = 1 2000 × 10 - 2   m = 5 × 10 - 6   m