The distance between the object and the eyepiece of a compound microscope is 25.0 cm. The focal length of its objective lens is 0.200 cm and the eyepiece has a focal length of 2.60 cm. What is the total magnification of the microscope when used by the person of normal eyesight?
A) -1070
B) -204
C) -520
D) -477
E) -772

Question

Quizplus · Accepted Answer

The total magnification of a compound microscope is given by the product of the magnifications of the objective and the eyepiece. The magnification of the objective is given by the formula M_obj = L / f_obj, where L is the tube length (25.0 cm) and f_obj is the focal length of the objective (0.200 cm). The magnification of the eyepiece is given by M_eye = 25 / f_eye, where 25 cm is the near point distance for normal eyesight and f_eye is the focal length of the eyepiece (2.60 cm). Calculating these gives M_obj = 125 and M_eye = 9.615, so the total magnification is M_total = M_obj * M_eye = 125 * 9.615 = -1070.

The Distance Between the Object and the Eyepiece of a Compound