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JEE Main 2023 (30 Jan, Shift 1) · Optical Instruments & the Eye

Optical Instruments & the Eye question from JEE Main 2023 (30 Jan, Shift 1)

Q18JEE Main 2023 · 30 JAN · SHIFT 1Medium

Optical Instruments & the Eye

A person has been using spectacles of power −1.0-1.0 dioptre for distant vision and a separate reading glass of power 2.02.0 dioptres. What is the least distance of distinct vision for this person:

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Answer: (a)

  1. Reading glass: P=+2P = +2 D, so f=+50f = +50 cm.
  2. It forms the image of a book at u=−25u = -25 cm at the person's near point.
  3. 1v=1f+1u=150−125=−150⇒v=−50\dfrac{1}{v} = \dfrac{1}{f} + \dfrac{1}{u} = \dfrac{1}{50} - \dfrac{1}{25} = -\dfrac{1}{50} \Rightarrow v = -50 cm.
  4. So the answer is (a) 50 cm.
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