Question

A microscope's objective lens has focal length 6.71 mm and is being used to produce an image of a bacterium (the object). The bacterium is located 9.98 mm from the objective lens. The eyepiece lens has focal length 198 mm. How far away must the eyepiece lens be placed in order for the image produced by the objective lens to fall directly onto the eyepiece's focus (the one near the objective lens)?

Answer 1

IN THE QUESTION IT IS GIVEN THAT

f(objective)/fo=6.71mm

f(eyepiece)/fe=198mm

distance of the object,do=9.98mm

using the lens formula

(v=image distance,u=object distance)

for the objective lens

[in metre]

v=20.41m

now for the image to lie on the focus of eyepiece exactly

let L be the distance between the objective elns and the eyepiece lens

therefore,

L=V+fe

L=20+198(mm)=218mm=0.2m

ANSWER: the eyepiece must be place 0.2m away from the objective lens so that the image formed by the objective lens is obtined at the focus of the eyepiece.