Question

Large aperture of telescope is used for

• A. Large image
• B. Greater resolution
• C. Reducing lens aberration
• D. Ease of manufacture

Answer 1

The correct option is B Greater resolution

The resolving power of an astronomical telescope is,

$R=\frac{D}{1.22\lambda }$

Where, $D=$ is the diameter of the objective lens.

In order to improve the resolution of an astronomical telescope, one has to increase the diameter of the objective lens.

In an astronomical telescope, the objective is of large focal length while the eyepiece of smaller focal length.

Larger aperture of objective helps in improving the
brightness of image by gathering more light from
the distant object. However, it increases aberrations
particularly spherical.

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(B\right)$ is the correct answer.