Question

The aperture of the objective lens of a telescope is made large so as to:

• A. increase the resolving power of the telescope
• B. increase the magnifying power of the telescope
• C. to focus on distant objects
• D. make image aberration less

Answer 1

Answer: (A)

increase the resolving power of the telescope

Resolving power of the telescope $RP=\frac{a}{1.22\lambda }$

where $a$ is the diameter (aperture) of the objective lens.

$⟹$ $RP\propto a$

Thus the aperture of the objective lens is made so large so as to increase the resolving power of the telescope.