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. (a) half minute
B. (b) one degree
C. ( c ) half degree
D. (d) one minute

Answer

D

Explanation

(d) `30 Division sof vernier scale coincide with `29` divisions of main scales
Therefore `1 V.S.D = (29)/(30)MSD`
Least count = 1MSD - 1VSD = 1MSD - (29)/(30)MSD`
`=(1)/(30)/(MSD) = (1)/(30) xx 0.5@ = 1minute`.