Question

Why is the objective lens of an optical telescope
made very large?
To collect the maximum light possible.
To avoid interference.
To make the image as bright as possible.
To reduce cost.​

Answer 1

Answer:

To collect the maximum light possible.

That means the tube has to be at least as long as the focal length. Since reflectors use mirrors, they can be shorter than their focal length. By reflecting light between multiple mirrors, the light still travels the full focal length.

hope it helps you