The diameter of objective lens of a telescope is 6 cm and wavelength of light used is 540 nm. The resolving power of telescope is

$\mathrm{D}=6\mathrm{cm}=6\times {10}^{-2}\mathrm{m}$
And wavelength,
$\mathrm{\lambda }=540\mathrm{nm}=540\times {10}^{-9}\mathrm{m}$
Resolving power of telescope(RP)
$=\frac{1}{\mathrm{\Delta \theta }}=\frac{\mathrm{D}}{1.22\mathrm{\lambda }}$
Where, D=diameter of objective and
$\mathrm{\lambda }=$wavelength of light
$\begin{array}{l}\Rightarrow \mathrm{RP}=\frac{6\times {10}^{-2}}{1.22\times 540\times {10}^{-9}}{\mathrm{rad}}^{-1}\\ =\frac{6000\times {10}^4}{540\times 1.22}{\mathrm{rad}}^{-1}=9.1\times {10}^4{\mathrm{rad}}^{-1}\end{array}$