The objective lens 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,with the final image viewed at infinity.The near point of the microscope user is at 25 cm.What is the distance between the object and the focal point of the objective lens?
A)0.13 mm
B)0.18 mm
C)0.23 mm
D)0.28 mm
E)0.33 mm

Question

Quizplus · Accepted Answer

The correct answer is A.The distance between the object and the focal point of the objective lens is 0.13 mm. This can be calculated using the thin lens equation:1/f = 1/do + 1/diwhere f is the focal length of the lens, do is the object distance, and di is the image distance.In this case, the focal length of the objective lens is 4.0 mm, the image distance is 30 times the object distance, and the final image is viewed at infinity. So, we have:1/4 = 1/do + 1/30doSolving for do, we get:do = 0.13 mm

The Objective Lens and the Eyepiece of a Microscope Have