Situation 19.2
The objective and the eyepiece of a microscope have focal lengths of 4.0 mm and 25 mm,respectively.The objective produces a real image 30 times the size of the object.The final image is viewed at infinity.The near point of the microscope user is at 25 cm.
-In Situation 19.2,the distance between the object and the focal point of the objective,in mm,is closest to:
A)0.13
B)0.18
C)0.23
D)0.28
E)0.33

Question

Quizplus · Accepted Answer

The distance between the object and the focal point of the objective is given by:$$d_o = \frac{f_o}{M-1}$$where:* $d_o$ is the distance between the object and the focal point of the objective* $f_o$ is the focal length of the objective* $M$ is the magnification of the objectiveIn this case, $f_o = 4.0$ mm and $M = 30$. Therefore,$$d_o = \frac{4.0 	ext{ mm}}{30-1} = 0.13 	ext{ mm}$$Therefore, the correct answer is A.

Situation 19.2 The Objective and the Eyepiece of a Microscope Have Focal