The defective eye of a person has near point 0.5 and point 3 metre the power for corrective lens required for
1,reading purpose and
2,seeing distant object,respectively are:-
(a)0.5D and +3D
(b)+2D and -13D
(c)-2D and +13D
(d)0.5D and -3.0D
(PLEASE READ THE QUESTION CAREFULLY AND WRITE WITH DEFINITION SO THAT I WILL MARK IT AS BRAINLIEST ANSWER)
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jaiveersingh1234
Gopalswamy
03.02.2020
Physics
Secondary School
+5 pts
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The defective eye of a person has near point 0.5m and point 3m. The power far corrective lens required for (i) reading purpose and (ii) seeing distant objects, respectively are:
(a) 0.5D and +3D
(b) +2D and -1/3D
(c) -2D and +1/3D
(d) 0.5D and -3.0D
2
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abhi178
Abhi178★ Brainly Teacher ★
answer : option (B) +2D and -1/3 D
(1) reading purpose,
v = -50cm , u = -D = -25 cm [ for human eyes ]
now applying lens maker formula,
1/f = 1/v - 1/u
= 1/-50 - 1/-25
= 1/-50 + 1/25
= 1/50
f = 50cm
so, power of lens is P = 100/f = 100/50 = +2D [ here D is dioptre ]
(2) seeing distinct objects,
u = ∞ , v = -3m = -300cm
using lens maker formula,
1/f = 1/-300 - 1/∞
= -1/300
f = -300
so, power of lens is P' = 100/-300 = -1/3 D