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25/09/2021 6:52 pm
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A person needs a lens of power -5.5 D for correcting his distant vision. For correcting his near vision, he needs a lens of power +1.5 D. What is the focal length of the lens required for correcting
(a) distant vision?
(b) near vision?
1 Answer
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25/09/2021 7:00 pm
(a) Given: For distant vision, P = -5.5 D
∴ Focal length, f = \(\frac{100}{-5.5}\)
= -18.2 cm
(b) Given: For near vision, P = 1.5 D
∴ Focal length, f = \(\frac{100}{1.5}\)
= 66.7 cm