A watch-maker keeps two alternative working arrangements while inspecting tiny gear…
PHYSICS · Multi-part · CBSE · Physics · Ray Optics and Optical Instruments · Ray Optics and Optical Instruments
Problem
A watch-maker keeps two alternative working arrangements while inspecting tiny gear teeth with the same hand-held lens.
(i) Define the term "normal adjustment" for a simple magnifier.
(ii) The watch-maker can either place the lens so that the final image is 25cm in front of his eye or so that it is at infinity. Explain, with reference to the functioning of the eye, which of the two placements minimises muscular strain.
(iii) Justify why many professionals still prefer the infinity setting even though the apparent size is smaller.