A student measured the length of a rod and wrote it as `3.50 cm`. Which instruments dis he use to measure it ?

Options

A. A meter scale
B. Avernier scale matches with 9 division in main scale and main scale has 10 divisions in 1cm
C. A screw gausge having 100 divisions the circular scale and pitch as 1mm
D. A screw gausge having 50divisions the circular scale and pitch as 1mm

Explanation

If student measure `3.50cm` it means that there in an uncertainly of order `0.01cm`
`L.C` of `V.C = 1MSD - 1VSD`
`=(1)/(10) [1 - (9)/(10)] = (1)/(100) cm`
So `B` is correct option .