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. 1 minute
B. half minute
C. one degree
D. half degree

Answer

A

Explanation

Given, 30 VSD exactly match with 29 division of main scale division MSD
One unit of vernier scale division
`1VSD= (29)/(30)MSD`
Least count, LC= 1MSD-1VSD
`=(1)/(30)`MSD
1MSD is equal to 0.5 degrees. `[1^(@)=60" minutes "]`
`(1)/(30)` MSD is the `(1)/(30)xx30` minutes
So, least count is 1 minute