Question

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. 

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Answer 1

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 5 × 10^-6 m. 

Explanation:

We have

49 MSD = 50 VSD

1 VSD = `49/50` MSD

So, L.C = 1 MSD - 1 VSD = 1 MSD `-49/50` MSD

= `1/50`MSD = `1/50xx1/40`cm = `1/2000`cm

= `10000/2000xx10^4`

= 5 × 10^-4 m = 5 × 10^-6 m.