Question

The magnifying power of a converging lens used as a simple microscope is $\left(1+\frac{D}{f}\right).$ A compound microscope is a combination of two such converging lenses. Why don't we have magnifying power $\left(1+\frac{D}{f_o}\right)\left(1+\frac{D}{f_e}\right)?$ In other words, why can the objective not be treated as a simple microscope but the eyepiece can?

Answer 1

In a simple microscope, the converging lens is used to magnify the object. It is done by the eyepiece in a compound microscope. But the purpose of the objective lens is the same, i.e., to form an enlarged, real and inverted image of the object at a distance less than the focal length of the eyepiece. So, its magnification power cannot be expressed in a way it is expressed for a simple microscope.