Question

A tacheometer was used to determine the horizontal distance of a point from the instrument station. The pitch of screw is 0.1 mm. The micrometer reading of the drum of the diaphragm were 3.125 and 3.450 respectively when the staff intercept was 2.5 m. The focal length of the object glass was 220 mm. The distance of the instrument axis from the centre of the object glass measured is 20 cm. The horizontal distance between the instrument and the point (staff locate) is _______ kms.

• A. 0.836

Answer 1

The correct option is A 0.836
Given, f = 220 mm = 22 cm

P = 0.1 mm = 0.01 cm

m = 3.125 + 3.450 = 6.575

d = 20 cm

s = 2.5 m

Now,

$k=\frac{f}{p}=\frac{22}{0.01}=2200$

C = f + d = 22 + 20 = 42 cm

$\therefore$ Horizontal distance ,

$D=\frac{ks}{m}+c$

$=\frac{2200\times 2.5}{6.575}+0.42$

$=836.92m$

$=0.836km$