$A$ man can clearly see two poles at a distance of $11 \, km$. What should be the minimum distance between the poles in $m$?

The diameter of a human eye lens is $2\,mm$. What will be the minimum distance between two points to resolve them,if they are situated at a distance of $50\,m$ from the eye? The wavelength of light used is $5000\,\mathring{A}$.

When a beam of light is used to determine the position of an object,the maximum accuracy is achieved if the light is

An electron microscope is operated at $40 \ kV$. The ratio of the resolving power of this microscope to another one which uses yellow light of wavelength $6 \times 10^{-7} \ m$ is:

Two parallel pillars are $11 \, km$ away from an observer. The minimum distance between the pillars so that they can be seen separately will be.....$m$

If a microscope is placed in air,the minimum separation of two objects seen as distinct is $6 \mu m$. If the same is placed in a medium of refractive index $1.5$,then the minimum separation of the two objects to be seen as distinct is: (in $\mu m$)