In finding out refractive index of glass slab the following observations were made through travelling microscope 50 vernier scale division = 49 MSD; 20 divisions on main scale in each cm
For mark on paper MSR = 8.45 cm, VC = 26
For mark on paper seen through slab MSR = 7.12 cm, VC = 41
For powder particle on the top surface of the glass slab MSR = 4.05 cm, VC = 1
(MSR = Main Scale Reading, VC = Vernier Coincidence)
Refractive index of the glass slab is:

Question

In finding out refractive index of glass slab the following observations were made through travelling microscope 50 vernier scale division = 49 MSD; 20 divisions on main scale in each cm

For mark on paper MSR = 8.45 cm, VC = 26

For mark on paper seen through slab MSR = 7.12 cm, VC = 41

For powder particle on the top surface of the glass slab MSR = 4.05 cm, VC = 1

(MSR = Main Scale Reading, VC = Vernier Coincidence)

Refractive index of the glass slab is:

G1 Physics · Accepted Answer

1 MSD = 1/20 cm = 0.05 cm 50 VSD = 49 MSD Therefore: 1 VSD = (49/50)(0.05) = 0.049 cm Least count: LC = 1 MSD - 1 VSD = 0.001 cm For mark on paper: L₁ = 8.45 + 26(0.001) = 8.476 cm For mark seen through slab: L₂ = 7.12 + 41(0.001) = 7.161 cm For powder particle on top surface: L₃ = 4.05 + 1(0.001) = 4.051 cm Actual thickness: t = L₁ - L₃ = 4.425 cm Apparent thickness: t' = L₂ - L₃ = 3.110 cm Refractive index: μ = t/t' = 4.425/3.110 ≈ 1.42