Q5. A myopic person can clearly see objects between 40 cm and 200 cm without spectacles. After wearing spectacles close to the eye to correct distant vision, the nearest clear object is at:
Options

Question

Q5. A myopic person can clearly see objects between 40 cm and 200 cm without spectacles. After wearing spectacles close to the eye to correct distant vision, the nearest clear object is at:

G1 Physics · Accepted Answer

GIVEN: Near point = 40 cm and far point = 200 cm before correction. Spectacles are close to the eye. Step 1: Full distant-vision correction requires the spectacle focal length f = −200 cm. Step 2: The closest clearly seen object through spectacles must form a virtual image at the original near point: v = −40 cm. Step 3: Let the new near point be x, so u = −x. Apply 1/f = 1/v − 1/u. Step 4: −1/200 = −1/40 + 1/x ⇒ 1/x = 1/40 − 1/200 = (5 − 1)/200 = 1/50. Step 5: x = 50 cm; thus correcting myopia…