Question 353: Ray Optics

Question

A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since :

Accepted Answer

With larger aperture of objective lens, the light
gathering power in telescope is high.
Also, the resolving power or the ability to observe two
objects distinctly also depends on the diameter of
the objective. Thus objective of large diameter is
preferred.
Also, with large diameters fainter objects can be
observed. Hence it also contributes to the better
quality and visibility of images.
Hence, all options are correct.

Answer

a large aperture contributes to the quality and visibility of the images.

Answer

a large area of the objective ensures better light gathering power.

Answer

a large aperture provides a better resolution.

Answer

All the above.

Ray Optics

A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since :

Choose the correct answer: