Question

A telescope is used to resolve two stars separated by 4.6×10^-6rad. If the wavelength of light used is 5460Å, what should be the aperture of the objective of the telescope?

• A. 0.1488 m
• B. 0.567 m
• C. 1 m
• D. 2 m

Answer 1

Answer: (A)

0.1488 m

Answer 2

Aperture of the telescope

$D = \frac{1.22\lambda}{d\theta}$

Here, $\lambda = 5460Å = 5460 \times 10^{- 10}m,d\theta = 4.6 \times 10^{- 6}rad$

$\therefore D = \frac{1.22 \times 5460 \times 10^{- 10}}{4.6 \times 10^{- 6}} = 0.1488m$