• # question_answer A telescope using light having wavelength $5000\overset{\text{o}}{\mathop{\text{A}}}\,$ and using lenses of focal lengths 2.5 cm and 30 cm. If the diameter of the aperture of the objective is 10 cm, then the resolving limit of telescope is A)  $6.1\times {{10}^{-6}}rad$                       B)  $5.0\times {{10}^{-6}}rad$ C)  $8.3\times {{10}^{-4}}rad$                                   D)  $7.3\times {{10}^{-3}}rad$

$m=\frac{{{f}_{o}}}{{{f}_{e}}}=\frac{30}{2.5}=12$ Resolving limit $=\frac{1.22\lambda }{a}=\frac{1.22\times (5000\times {{10}^{-10}})}{0.1}$                 $=6.2\times {{10}^{-6}}rad$