What is meant by the resolving power of a telescope? State any one method of increasing the resolving power of an astronomical telescope.

In viewing through a magnifying glass, we put our eye quite close to the lens. Does angular magnification change, if the eye ¡s moved away from the lens?

The magnifying power of a simple microscope is inversely proportional to the focal length of the lens. Then, why can we not obtain a very high magnifying power by using a lens of very small focal length?

In a compound microscope, both the objective and the eye-piece should be of small focal lengths. Why?

Two lenses of focal lengths $5 \mathrm{cm}$ and $50 \mathrm{cm}$ are to be used for making a telescope. Which lens will you use for the objective?

An astronomical telescope uses two lenses of powers $10$ dioptre and $1$ dioptre. If the final image of a distant object is formed at infinity, calculate the length of the telescope.

Explain the working of a simple microscope and show that its angular magnification is given by $M=1+\left(\raisebox{1ex}{${\displaystyle D}$}\!\left/ \!\raisebox{-1ex}{$f$}\right.\right)$, where $D$ is the least distance of distinct vision.