A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since:
- a large aperture contributes to the quality and visibility of the images.
- a large area of the objective ensures better light gathering power.
- a large aperture provides a better resolution.
- all of the above.
The Correct Option is D
Solution and Explanation
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Concepts Used:
Spherical Mirrors
A spherical mirror is a mirror which has been cut out of a spherical surface.
There are two kinds of spherical mirrors:
- Convex Mirror
- Concave Mirror
Concave Mirror
Concave mirrors are also called converging mirrors, because in these types of mirrors, light rays converge at a point after impact and reflect back from the reflective surface of the mirror.
Convex Mirror
The convex mirror has a reflective surface that is curved outward. Regardless of the distance between the subject and the mirrors, these mirrors are "always" virtual, upright and reduced.