In a vernier calliper, vernier scale has 20 division which match with `19^(th)` division of main scale. The least count of main scale is 1 mm. When two jaws of vernier calliper is in contact, zero of main scale is visible and `14^(th)` vernier scale division match with a main scale division. In measuring the length of iron rod by this instrument, main scale reads 35 division and `8^(th)` division of vernier scale coincides with a main scale division. Find length of rod in cm.

Answer

3.47

Explanation

MSD = 0.1 cm
20 VSD = 19 MSD
Least count = MSD - VSD = 0.005cm +ve zero error = `14 xx LC = .070 cm`
measured length
`= MSR + VSR xx LC - (+ve "error")`
`= 3.5 xx 0.1 + 8 xx 0.005 - 0.070`
`= 3.5 + 0.040 - 0.070`
`=3.500 - 0.030 = 3.47 cm`.