Question

Two poles are separated by a distance of $3.14m$. The resolving power of human eye is $1$ minute of an arc. The maximum distance from which he can identify the two poles distinctly is

• A. 10.8 km
• B. 5.4 km
• C. 188 m
• D. 376 m

Answer 1

Answer: (A)

Given the lateral separation of the poles $d=3.14m$
The resolving power of the eye is
$\theta =1\min =\pi /(60\times 180)$ rad
The maximum distance from which poles are distinctly visible is
$D=d/\theta$
$\Rightarrow D=(3.14\times 60\times 180)/\pi$
$=10800m=10.8km$