Question

A spectrometer gives the following reading when used to measure the angle of a prism.
Main scale reading : `58.5 degree`
Vernier scale reading : `09` divisions
Given that `1` division on main scale correspods to `0.5` degree. Total divisions on the vernier scale is `30` and match with `29` divisions of the main scale. the angle of the prism from the above data:
A. (a) `58.59 degree`
B. (b) `58.77 degree`
C. ( c ) `58.65 degree`
D. (d) `59 degree`

Answer 1

Correct Answer - C
( c ) `because` Reading of vernier = Main scale reading + Vernier scale reading xx least count`.
Main scale reading = 58.5`
`Vernier scale reading = 09 division`
`least count of Vernier = 0.5@//30`
Thus `R = 58.5@ + 9 xx (0.5@)/(30)`
`R = 58.65`