A watch-repairer can adjust his lens so that the object–lens distance is such that…

PHYSICS · Subjective · CBSE · Physics · Ray Optics and Optical Instruments · Ray Optics and Optical Instruments

Problem

A watch-repairer can adjust his lens so that the object–lens distance is such that the final image is either (a) at infinity or (b) at

25\,\text{cm}

from the eye. Which adjustment will minimise strain on his eyes? Give a brief reason.