alleryA bifocal lens used for presbyopia + myopia has:
AUpper convex portion and lower concave portion
BUpper concave portion and lower convex portion
CTwo convex portions of equal power
DTwo concave portions of equal power
Answer & Solution
Correct answer: B. Upper concave portion and lower convex portion
1. Distant vision needs a concave lens, used for looking ahead — placed on top.
2. Near vision (reading) needs a convex lens — placed at the bottom.
3. The bifocal stacks the two together.
_Source: syllabus Science, Ch 10 "The Human Eye and the Colourful World", §10.2_
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