Reading glasses of what power are needed for a person whose near point is 50.0 cm, so that she can read clearly the print of a book located at 25.0 cm? Assume a lens-eye distance of 2.00 cm.
Solution)
Given,
di = 50 cm
do = 25 cm
f = ?
Now,
(1/25) + (1/-50) = (1/f)
f = 50 cm=0.5 m
Now , Power of lens
P = (1/f)
P= (1/.5) = 2 dp
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