The "tube length" of a microscope is defined to be the difference between the (objective) image distance and objective focal length: L = di - ƒobjective. Many microscopes are standardized to a tube length of L = 160 mm. Consider such a microscope whose objective lens has a focal length ƒobjective = 7.50 mm.
(a) How far from the object should this lens be placed?
(b) What focal length eyepiece would give an overall magnification of -55?
(c) What focal length eyepiece would give an overall magnification of -110?