A man's near point is 0 . 5 m and the far point is 3 m . Power of spectacle lenses required for (i) reading purposes (ii) seeing distant objects, respectively are

Question

A man's near point is 0 . 5 m and the far point is 3 m . Power of spectacle lenses required for (i) reading purposes (ii) seeing distant objects, respectively are, - 2 D and + 3 D, + 2 D and - 3 D, + 2 D and - 0 . 33 D, - 2 D and + 0 . 33 D

MARKS App · Accepted Answer

For reading purpose u = - 25 c m , v = - 50 c m , f = ? ∴ 1 f = 1 v - 1 u = 1 50 + 1 25 = 1 50 P = 100 f = + 2 D For distinct vision, f ′ = distance of far point = - 3 m P = 1 f ′ = - 1 3 D = - 0 . 33 D

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