You are given two convex lenses of short aperture having focal lengths 4 cm and 8 cm respectively.Which one of these will you use as an objective and which one as an eye piece for constructing a compound microscope?

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

You are given the following three lenses. Which two lenses will you use as an eye piece and as an objective to construct an astronomical telescope? Give reasons.

A compound microscope uses an objective lens of focal length 4 cm and eyepiece lens of focal length 10 cm. An object is placed at 6 cm from the objective lens. Calculate the magnifying power of the compound microscope. Also calculate the length of the microscope.

An angular magnification (magnifying power) of 30X is desired using an objective of focal length 1.25cm and an eyepiece of focal length 5cm. How will you set up the compound microscope?

A compound microscope is used to enlarge an object kept at a distance of 0.03 m from its objective, which consists of several convex lenses and has focal length 0.02 m .If a lens off focal length 0.1 m is removed from the objective, find out the distance by which the eye-piece of the microscope must be moved to refocus the image.