Q1. A myopic person has a far point of 80 cm and a near point of 20 cm. The person wears spectacles close to the eye that completely correct the myopia. The new near point measured from the spectacles is approximately:
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Question

Q1. A myopic person has a far point of 80 cm and a near point of 20 cm. The person wears spectacles close to the eye that completely correct the myopia. The new near point measured from the spectacles is approximately:

Options

G1 Physics · Accepted Answer

GIVEN: Original far point F = 80 cm; original near point N = 20 cm. Spectacles are close to the eye. Step 1: To correct distant vision, the concave lens must form a virtual image of infinity at the old far point. Therefore f = −80 cm. Step 2: For the closest readable object, the spectacle lens must form its virtual image at the original near point: v = −20 cm. Let u = −x, where x is the new near-point distance. Step 3: Lens formula: 1/f = 1/v − 1/u. Step 4: −1/80 = −1/20 + 1/x, so 1/x = 1/20 −…