The resolving limit of eye is `1min`. At a distance of `x km` from the eye, two persons stand with a lateral separation of `3m`. For the two persons to be just resolved by the naked eye, `x` shuold be

Options

A. `10 km`
B. `20 km`
C. `15 km`
D. `30 km`

Answer

A

Explanation

`theta = 1min = ((1)/(60))^(@) =(1)/(60)xx(pi)/(180) = (pi)/(10800) rad`

`theta = (3xx10^(-3))/(x)`
`x = (3xx10^(-3))/(theta) = (3xx10^(-3))/(pi//10800) = 10km`