A compound microscope is used to enlarge an object kept at a distance 0.03m from its object which consists of several convex lenses in contact and has focal length 0.02m. IF a lens of focal length 0.1m is removed from the objective. Find out the distance by which the eyepiece of the microscope must be moved to refocus the image.

A compound microscope is used to enlarge an object kept at a distance

1.	A compound microscope is used to enlarge an object kept at a distance 0.03m from its object which consists of several convex lenses in contact and has focal length 0.02m. IF a lens of focal length 0.1m is removed from the objective. Find out the distance by which the eyepiece of the microscope must be moved to refocus the image.
Answer» Solution :IF initially the objective forms the IMAGE at distance `v_1=1/v_1-1/(-3)=1/2 i.e, v_1=6cm` Now as in case of lenses in contact `1/F=1/f_1+1/f_2+…….or 1/F=1/f_1+1/F.` with `1/F.=1/f_2+1/f_3+….` So if ONE the lenses is REMOVED, the FOCAL length of the remaining lens system `1/F.=1/f-1/f_1=1/2 -1/10 i.e, F.=2.5cm` This lens will form the image of same OBJECT at a distance `v_2` such that `1/v_2-1/(-3)=1/2.5 i.e., v_2=15cm` So to refocus the image, eyepiece must be moved by the same distance through which the image formed by the objective has shifted i.e, 15-6=p cm away from the objective.