NEUROLOGY
VISUAL FIELD DEFECTS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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A near sighted person wears eye glass of power 5.5 D for distant vision. His doctor prescribes a correction of +1D in near vision part of his bi-focals, which is measured relative to the main part of the lens. Then, the focal length of his near vision part of the lens is
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-18.18 cm
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-20 cm
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+20.22 cm
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-22.22 cm
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Explanation:
Detailed explanation-1: -Solution. The person must be near-sighted because the person wears glasses of power –2.5 D. For a near-sighted person, u = ∞. So, the far point of the near-sighted person is 40 cm.
Detailed explanation-2: -Therefore, the focal length of the lens required for correcting distant vision will be =+66.7 cm.
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