Question

What is the minimum angular separation between two stars if telescope is used to observe them with an objective of circular aperture 20 cm? the wavelength of light used is 5900 $A^o$.

Answer 1

Aperture $=20cm=0.2m$

Wavelength $\lambda =5900A^o=5.9\times {10}^{-7}m$

Minimum angle separation,

$d\theta =\frac{1.22\lambda }{a}=\frac{1.22\times 5.9\times {10}^{-7}}{0.2}$

$=3.599\times {10}^{-6}rad$