Question

A person wants to see two pillars distant $11\text{km},$ separately. The distance between the pillars must be approximately (Resolving power of eye is $1^{\prime }$)

• A.
  $3.2\text{m}$
• B.
  $1\text{m}$
• C.
  $0.25\text{m}$
• D.
  $0.5\text{m}$

Answer 1

The correct option is A

$3.2\text{m}$
Resolving power of eye is

$R.P=1^{\prime }=\frac{1}{60}\times \frac{\pi }{180}\text{rad}$

Let the separation between the pillars be $x\text{m}$.



$\therefore \theta =\frac{x}{11000}$

$\Rightarrow \frac{1}{60}\times \frac{\pi }{180}=\frac{x}{11000}$

$\Rightarrow x=3.199\text{m}\approx 3.2\text{m}$

Hence, $\left(A\right)$ is the correct answer.