Which one of the following statements is con'ect about the magnification of an optical microscope ?

The total magnification of a compound microscope is the product of the linear magnification of the objective lens and the angular magnification of the eyepiece. The angular magnification of the eyepiece is mathematically expressed as M = 1 + (25 cm / f_eye), where f_eye is the focal length of the eyepiece. This formula demonstrates an inverse relationship: as the focal length of the eyepiece increases, its magnification power decreases. Similarly, the objective's magnification is approximately the tube length divided by its focal length, meaning magnification also decreases with an increase in the objective's focal length. Therefore, to achieve higher total magnification, lenses with shorter focal lengths are preferred. Consequently, magnification decreases with the increase in the focal length of the eyepiece, making option 4 the correct statement.