Question

There are 100 divisions on the circular scale of a screw gauge of pitch 1 mm. With no measuring quantity in between the jaws, the zero of the circular scale lies 5 divisions below the reference line. The diameter of a wire is then measured using this screw gauge. It is found the 4 linear scale divisions are clearly visible while 60 divisions on circular scale coincide with the reference line. The diameter of the wire is : 

(1) 4.65 mm 

(2) 4.55 mm 

(3) 4.60 mm 

(4) 3.35 mm

Answer 1

Correct option is : (2) 4.55 mm 

Least count \(=\frac{1}{100} \mathrm{~mm}=0.01 \mathrm{~mm}\) zero error \(=+0.05 \mathrm{~mm}\)

Reading \(=4 \times 1 \mathrm{~mm}+60 \times 0.01 \mathrm{~mm}-0.05 \mathrm{~mm}\) 

\(=4.55 \mathrm{~mm}\)