Angular magnification produced by a compound microscope
Example: The separation L between the objective (fo=0.5cm) and the eyepiece (fo=5cm) of a compound microscope is 7cm. Where should a small object be placed so that the eye is least strained to see the image and what is the angular magnification produced?
Solution: The eye is least strained if the final image is formed at infinitely. In such a case the image formed by objective should fall at the focus of eyepiece. As fo=5cm,L=7cm, this first image is formed at a distance = 7−5=2cm from objective. Thus v=+2cm. Also fo=0.5cm v1−u1=fo1 or, u1=v1−fo1=21−0.51 or, u=−32cm The object should be placed at 32cm from objective. Angular magnification = uv×feD=−322×525=−15