Question

The pitch of a screw gauge is 1 mm and there are 100 division on its circular scale. When nothing is put in between its jaws, the zero of the circular scale lies 4 divisions below the reference line. When a steel wire is placed between the jaws, two main scale divisions are clearly visible and 67 divisions on the circular scale are observed. the diameter of the wire is

Answer 1

Given:

The pitch of a screw gauge is 1 mm and there are 100 division on its circular scale.  

When nothing is put in between its jaws, the zero of the circular scale lies 4 divisions below the reference line.  

To find:

The diameter of the wire is

Solution:

From given, we have,

P = 1mm, N = 100  

The least count is given by, C = P/N = 1/100 = 0.01 mm

The instrument has a positive zero error, thus,

e = +NC = 4 × 0.01 = 0.04 mm

The main scale reading is 2 × (1 mm) = 2 mm

The circular scale reading is 67(0.01) = 0.67 mm

∴ The observed reading is R0 = 2 + 0.67 = 2.67 mm

The true reading = R0 − e = 2.67 - 0.04 = 2.63mm

Therefore, the diameter of the wire is 2.63 mm