Answer: length and size of the lens
Notes: Telescope and Microscope are two scientific instruments that serve their purposes differently. One of the main differences between a telescope and a microscope is that a telescope is used to view things that are far whereas a microscope is used to view things that are very near. The other differences between telescope and microscope include : (i) The aperture (lens diameter) is larger in case of telescope than in microscope. (ii) Focal point in case of telescope is far off but in case of microscope, it is just a fraction of an inch. (iii) In telescope, focal length of objective lens is large and that of eye piece is small but in microscope, the objective less has small length and eyepiece has longer focal length.
