Question

The angular resolution of a telescope of 10 cm diameter at a wavelength of 5000Å is of the order of:

• A. 10${}^6$ rad
• B. ${10}^{-2}$ rad
• C. ${10}^{-4}$ rad
• D. ${10}^{-5}$ rad

Answer 1

The correct option is D ${10}^{-5}$ rad

$R=\frac{1}{\Delta \theta }=\frac{a}{1.22\lambda }$
$\frac{1}{\Delta \theta }=\frac{0.10}{1.22\times 5000\times {10}^{-10}}$
$\Delta \theta =6.1\times {10}^{-6}rad$