Question

A person needs a lens of power 5.5 diopters for correcting his distant vision. For correcting his near vision he needs a lens of power + 1.5 diopter. What is the focal length of the lens required for correcting (i) distant vision, and (ii) near vision?​

Answer 1

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Answer 2

Answer:

(i) Distant Vision :

Given,

Power =5.5D

Power , P= 1/f

Focal length , f = 1/p

F = 1/ -5.5

F = 10/ -55

F = 2/ -11

F = 0.181m

F = -18.1 cm

(ii) Near Vision :

Given,

Power =1.5D

P = 1/f

F = 1/P

F = 1/1.5

F = 10/15

F = 2/3

F = 0.667m

F = 66.7m