Question

Calculate the limit of resolution of a telescope objective having a diameter of $200\, cm$, if it has to detect light of wavelength $500\, nm$ coming from a star :

• A. $305 \times 10^{-9}$ radian
• B. $152.5 \times 10^{-9}$ radian
• C. $610 \times 10^{-9}$ radian
• D. $457.5 \times 10^{-9}$ radian

Answer 1

Answer: (A)

Limit of resolution of telescope = $\frac{1.22 \lambda}{D}$
$\theta = \frac{1.22 \times 500 \times 10^{-9}}{200 \times 10^{-2}} = 305 \times 10^{-9}$ radian