in an experiment the angles are required to be using an instrument, `29` divisions of the main scale exactly coincide with the `30` divisions of the vernier scale. If the sallest division of the main scale is half- a degree `(= 0.5^(@)`, then the least count of the instrument is :

Options

A. One degree
B. Half degree
C. One minute
D. Half-minute

Answer

C

Explanation

Least count of vernier callipers
L.C = 1 MSD - 1 VSD
But here `29 MSD = 30 VSD rArr 1 VSD = (29)/(30)MSD`
`rArr L.C=1MSD-(29)/(30)MSD=`
`(1)/(30)MSD=(1)/(30)xx0.5^(@)=((1)/(60))^(@)=1` minute