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?

Two lenses of focal length 10 cm and -20 cm are placed in contact .What is the total power of the combination?

Two thin lenses of focal lenths + 10 cm and - 5 cm are kept in contact.What is the focal length and

Two thin converging lenses of focal lenths 15 cm and 30 cm are held in contact with each other.Calculate power and focal length of the combination.

Two thin lenses of focal lenths + 10 cm and - 5 cm are kept in contact.What is the power of combination.

Four lenses of focal length + 10 cm,+50 cm,+100 cm and + 200 cm are available for making an astronnomical tetescope.To produce the largest magnification,the focal length of the eye-piece should be

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?

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.