Help a the axis of a 0. At age 45, a person is fitted for reading glasses that h
ID: 1786761 • Letter: H
Question
Help a the axis of a 0. At age 45, a person is fitted for reading glasses that have a discovers herself holding her newspaper at a distance of 43.2 cm in order to see it clearly with her glasses on. Assume the glasses are eyes. power equal to 1.95 D in order to read at 25.0 cm. By the time she reaches the ag e of 55, she (a) Where was her near point at age 45? 43 (b) Where is her near point at age 55? (c) What power is now required for the lenses of her reading glasses so that she can again read at 25.0 cm?Explanation / Answer
(A) at 45,
f = 1/1.95 = 0.513 m = 51.3 cm
p = 25 -2.2 = 22.8 cm
1/f = 1/p + 1/q
1/51.3 = 1/22.8 + 1/q
q = - 41 cm
near point = 41 cm
(B) at the age of 55,
p = 43.2 - 2.2 = 41 cm
1/51.3 = 1/41 + 1/q
q = - 204 cm = - 2.04 m
her near point = 2.04 m
(c) 1/f = 1/22.8 - 1/204
f = 25.7 cm = 0.257 m
Power = 1/f = 3.90 D
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