why should objective of a telescope have larger focal length ?

Why should the objective of a telescope have large focal length and large aperture? Justify your answer.

Why should the objective of a telescope have focal length and large apearture ? Justify your answer .

Assertion : If objective and eye lenses of a microscope are interchanged then it can work as telescope. Reason : The objective of telescope has small focal length.

Assertion : If objective and eye lenses of a microscope are interchanged then it can work as telescope. Reason : The objective of telescope has small focal length.

The objective of a small telescope has focal length 120 cm and diameter 5 cm. The focal length of the eye piece is 2 cm. The magnifying power of the telescope for distant object is -

The aperture and focal length of the objective of telescope are large, why?

The aperture and focal length of the objective of telescope are large, why?