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Question
A doctor has prescribed a corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?
Solution
Power of lens,
P = +1.5 D,
P = `1/"f"`
f = `1/"P"`
= `1/(+1.5 "D")`
= +0.67 m
A convex lens has a positive focal length. Hence, it is a convex lens or a converging lens.
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