What is the focal length of the objective of an astronomical telescope as compared to that of the eyepiece?

$A$ ray of light $AB$ parallel to the principal axis is incident on a convex lens as shown in the figure. Copy the figure.
$(i)$ Draw the refracted ray.
$(ii)$ Name the point through which the refracted ray passes on the principal axis.

$A$ virtual,magnified and erect image can be formed by a concave mirror.

When an object is placed at $2F$ in front of a convex lens,where will its image be formed?

For a concave mirror,if the object distance $u = \infty$,then the image distance $v = ..........$.

$A$ point object emits rays in all directions. Consider a ray emitted from the object that is parallel to the principal axis of the mirror. One of the points required to trace the reflected ray is the point of incidence itself,as shown in the figure. Select a point from the given figure through which the reflected ray passes.