A screw gauge having `100` equal division and a pitch of length `1mm` is used to measue 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 fihure.
`(use pi = (22)/(7)`

Options

A. `2.1cm^(2)`
B. `2.6cm^(2)`
C. `5.2cm^(2)`
D. `1.3cm^(2)`

Answer

B

Explanation

`L.C=(0.5mm)/(50)=0.01mm`
Zero error `=5xxL.C=0.05mm`
`MSR=2xx0.5mm=1mm`
`CSR=25xx0.01mm=0.25mm`
So diameter`=MSR+CSR-Zero error =1.20mm`