What is the nature of the final image formed by an astronomical telescope compared to the object?

State Snell's law of refraction.

Draw the ray diagram in each case to show the position,nature,and size of the image formed when the object is placed:
$(i)$ At the centre of curvature of a concave mirror.
$(ii)$ Within the focal length of a convex lens.
$(iii)$ Between the pole and focus of a concave mirror.
$(iv)$ In front of a convex mirror.
$(v)$ In front of a concave lens.

What is the focal length of a convex lens having power $+5.0 \,D$?

$(a)$ Define radius of curvature and focal length of a spherical mirror and show it on a figure.
$(b)$ Write the relation between the radius of curvature and the focal length of a spherical mirror.

Which mirror has a large field of view?