Define the magnifying power of a compound microscope when the final image is formed at infinity . Why must both the objective and the eyepiece of a compound microscope has short focal lengths ? Explain.

Explanation

The magnification of compound microscope when the final image is formed at infinity, `m=L/(f_o)((D)/(f_e))`
For producing large magnifying power, both the objective and the eyepiece of a compound microscope should possess short focal length.
when ` f_(o) lt lt , f_e lt lt D,`
`m=(L/(f_o)-1)(1+D/(f_e)) ~~(L/(f_o)*D/(f_e))`