A screw gauge having `100` equal division and a pitch of length `1mm` is used to measure the diameter of a wire of length `5.6cm`. The main scale reading is `1mm and 47^(th)` circular division coincides with the scale. Find the curved surface area of wire in `cm^(2)` to appropriate significant figures.
use `pi = (22)/(7)`

Answer

B, C

Explanation

`Least Count = (1mm)/(100) = 0.01mm`
`Diameter = MSR + CSR xx (least count)`
`=1mm + 47 xx (0.01)mm = 1.47mm`
`Surface Area = piDl`
`=(22)/(7) xx 1.47 xx56mm^(2) = 2.58724cm^(2)`
`= 2.6cm^(2)` (Rounding off to two significant figures)