In an optical instrument,the wavelengths of light used are $\lambda_1 = 4000 \ \mathring{A}$ and $\lambda_2 = 5000 \ \mathring{A}$. What is the ratio of their resolving powers?

The limit of resolution of an oil immersion objective microscope of numerical aperture $0.8$ for light of wavelength $0.6 \mu m$ is

For a telescope to have large resolving power,the

For a given wavelength,telescopes with large aperture objectives are used for:

The resolving power of the human eye is $1'$. At what distance $r$ (in $km$) can two objects separated by a distance of $d = 3 \, m$ be seen as distinct?

Two points separated by $0.05 \, mm$ can just be inspected in a microscope when light of wavelength $6000 \, \mathring{A}$ is used. If light of wavelength $3000 \, \mathring{A}$ is used,then the limit of resolution becomes ........... $mm$.